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    Vitamin K

    Uses

    Vitamin K is needed for proper bone formation and blood clotting. In both cases, vitamin K does this by helping the body transport calcium . Vitamin K is used by doctors when treating an overdose of the drug warfarin . Also, doctors prescribe vitamin K to prevent excessive bleeding in people taking warfarin but requiring surgery.

    There is promising preliminary evidence that vitamin K2 (not vitamin K1), may improve a group of blood disorders known as myelodysplastic syndromes,1 which carry a significantly increased risk of progression to acute myeloid leukemia.

    What Are Star Ratings?

    Our proprietary "Star-Rating" system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

    For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

    3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

    2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

    1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

    This supplement has been used in connection with the following health conditions:

    Used for Why
    2 Stars
    Anorexia
    Take under medical supervision: 45 mg daily
    In people with anorexia, supplementing with vitamin K2 may help prevent osteoporosis.

    In a preliminary study of women with anorexia nervosa, those who supplemented with 45 mg of vitamin K2 per day for approximately one year experienced significantly less bone loss, compared with women who did not take the supplement.2 This study suggests that supplementing with vitamin K2 may help prevent osteoporosis , which is a common complication of anorexia nervosa. The amount of vitamin K2 used in this study was much larger than the amount of vitamin K found in food and most supplements. Moreover, vitamin K2 is not yet generally available as a supplement, although it can be obtained through some nutritionally oriented doctors. Individuals interested in using this treatment should be monitored by a doctor.

    2 Stars
    Atherosclerosis (Vitamin K1, for coronary calcification )
    500 mcg per day of vitamin K1
    In a double-blind trial, supplementing with vitamin K1 for three years appeared to slow the rate of progression of coronary artery calcification in seniors.
    In a double-blind trial, supplementing with vitamin K1 for three years appeared to slow the rate of progression of coronary artery calcification in elderly people who had preexisting coronary artery calcification. Participants in that study were randomly assigned to receive a multivitamin that contained 500 mcg per day of vitamin K1 or the same multivitamin without vitamin K1.3
    2 Stars
    Celiac Disease
    Consult a qualified healthcare practitioner
    The malabsorption that occurs in celiac disease can lead to multiple nutritional deficiencies. Supplementing with vitamin K may correct a deficiency.

    The malabsorption that occurs in celiac disease can lead to multiple nutritional deficiencies. The most common nutritional problems in people with celiac disease include deficiencies of essential fatty acids, iron , vitamin D , vitamin K , calcium , magnesium , and folic acid .4 Zinc malabsorption also occurs frequently in celiac disease5 and may result in zinc deficiency, even in people who are otherwise in remission.6 People with newly diagnosed celiac disease should be assessed for nutritional deficiencies by a doctor. Celiac patients who have not yet completely recovered should supplement with a high-potency multivitamin-mineral . Some patients may require even higher amounts of some of these vitamins and minerals-an issue that should be discussed with their healthcare practitioner. Evidence of a nutrient deficiency in a celiac patient is a clear indication for supplementation with that nutrient.

    After commencement of a gluten-free diet, overall nutritional status gradually improves. However, deficiencies of some nutrients may persist, even in people who are strictly avoiding gluten. For example, magnesium deficiency was found in 8 of 23 adults with celiac disease who had been following a gluten-free diet and were symptom-free. When these adults were supplemented with magnesium for two years, their bone mineral density increased significantly.7

    2 Stars
    Crohn's Disease
    80 to 1,000 mcg daily
    Taking vitamin K can counteract the deficiency and resulting bone loss that can occur in people with Crohn's disease.

    In people with Crohn's disease, vitamin K deficiency can result from malabsorption due to intestinal inflammation or bowel surgery, from chronic diarrhea, or from dietary changes necessitated by food intolerance. In addition, Crohn's disease is often treated with antibiotics that have the potential to kill beneficial vitamin K-producing bacteria in the intestines. Vitamin K levels were significantly lower in a group of people with Crohn's disease than in healthy people. Moreover, the rate of bone loss in the Crohn's disease patients increased with increasing degrees of vitamin K deficiency.8 When combined with earlier evidence that vitamin K is required to maintain healthy bones, this study suggests that vitamin K deficiency is a contributing factor to the accelerated bone loss that often occurs in people with Crohn's disease.

    2 Stars
    Cystic Fibrosis
    5 mg every three days
    The fat malabsorption associated with cystic fibrosis often leads to a deficiency of fat-soluble vitamins, such as vitamin K. Supplementation can help counteract the deficiency.

    The fat malabsorption associated with CF often leads to a deficiency of fat-soluble vitamins. Oral supplementation of these nutrients is considered crucial to maintaining good nutritional status.9 Current recommendations for supplementation are as follows: vitamin A , 5,000 to 10,000 IU/day; vitamin D , 1,000 to 2,000 IU/day; vitamin E , 100 to 300 IU/day; and vitamin K , 5 mg every three days. Of the water-soluble vitamins, only vitamin B12 is poorly absorbed in cystic fibrosis,10 and taking pancreatic enzymes helps prevent B12 deficiencies.11

    2 Stars
    Osteoporosis
    1,000 mcg daily
    Vitamin K is needed for bone formation, and supplementing with it may be a way to maintain bone mass.

    Vitamin K is needed for bone formation. People with osteoporosis have been reported to have low blood levels12 , 13 and low dietary intake of vitamin K.14 , 15 One study found that postmenopausal (though not premenopausal) women may reduce urinary loss of calcium by taking 1 mg of vitamin K per day.16 People with osteoporosis given large amounts of vitamin K2 (45 mg per day) have shown an increase in bone density after six months17 and decreased bone loss after one18 or two19 years.

    Other preliminary studies have reported that vitamin K supplementation increases bone formation in some women20 and that higher vitamin K intake correlates with greater bone mineral density.21 However, a double-blind study found that supplementing with 500 mcg of vitamin K1 per day for three years had no effect on bone mineral density, when compared with a placebo.22 Some doctors recommend 1 mg vitamin K1 to postmenopausal women as a way to help maintain bone mass, though optimal intake remains unknown.

    1 Star
    Morning Sickness
    Refer to label instructions
    Vitamin K and vitamin C, taken together, may provide relief of morning sickness symptoms for some women.

    Vitamin K and vitamin C , taken together, may provide relief of symptoms for some women. In one study, 91% of women who took 5 mg of vitamin K and 25 mg of vitamin C per day reported the complete disappearance of morning sickness within three days.23 Menadione was removed from the market a number of years ago because of concerns about potential toxicity. Although some doctors still use a combination of vitamin K1 (the most prevalent form of vitamin K in food) and vitamin C for morning sickness, no studies on this treatment have been done.

    1 Star
    Phenylketonuria
    Refer to label instructions
    People with PKU may be deficient in vitamin K, due to the restricted PKU diet. Supplementing with vitamin K may correct a deficiency.

    People with PKU may be deficient in several nutrients, due to the restricted diet which is low in protein and animal fat. Deficiencies of long-chain polyunsaturated fatty acids (LC-PUFAs),24 , 25 , 26 selenium ,27 , 28 , 29 , 30 vitamin B12 ,31 and vitamin K may develop on this diet.32

    Because the PKU diet is low in animal products, fat intake is also significantly reduced. The results of a preliminary study of children with PKU suggested that the low-fat PKU diet intake may impair the absorption of vitamin K , a fat-soluble vitamin, from the diet, possibly resulting in a vitamin K deficiency. In that study, children with PKU on a strict diet had low levels of certain vitamin K-dependent proteins needed for normal blood clotting.33

    How It Works

    How to Use It

    The recommended dietary allowance for vitamin K is about 1 mcg per 2.2 pounds of body weight per day or about 65 to 80 mcg per day for most adults.34 This level of intake may be achieved by consuming adequate amounts of leafy green vegetables. However, studies have shown that many men and women aged 18 to 44 years ingest less than the recommended amount of vitamin K.35 , 36

    Where to Find It

    Leafy green vegetables, such as spinach, kale, collards, and broccoli, are the best sources of vitamin K. The greener the plant, the higher the vitamin K content.37 Other significant dietary sources of vitamin K include soybean oil, olive oil, cottonseed oil, and canola oil.38

    Possible Deficiencies

    A vitamin K deficiency, which causes uncontrolled bleeding, is rare, except in people with certain malabsorption diseases . However, there are reports of severe vitamin K deficiency developing in hospitalized patients who had poor food intake and were receiving antibiotics.39 All newborn infants receive vitamin K to prevent deficiencies that sometimes develop in breast-fed infants.

    Interactions

    Interactions with Supplements, Foods, & Other Compounds

    Vitamin K facilitates the effects of calcium in building bone and proper blood clotting.

    Interactions with Medicines

    Certain medicines interact with this supplement.

    Types of interactions: Beneficial Adverse Check

    Replenish Depleted Nutrients

    • Ceftibuten

      Several cases of excessive bleeding have been reported in people who take antibiotics.40 , 41 , 42 , 43 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.44 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Ceftizoxime

      Several cases of excessive bleeding have been reported in people who take antibiotics.45 , 46 , 47 , 48 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.49 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Ceftriaxone

      Several cases of excessive bleeding have been reported in people who take antibiotics.50 , 51 , 52 , 53 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.54 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Cefuroxime

      Several cases of excessive bleeding have been reported in people who take antibiotics.55 , 56 , 57 , 58 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.59 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Cephalothin

      Several cases of excessive bleeding have been reported in people who take antibiotics.60 , 61 , 62 , 63 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.64 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Cephapirin

      Several cases of excessive bleeding have been reported in people who take antibiotics.65 , 66 , 67 , 68 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.69 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Cholestyramine

      Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .70 , 71 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.72 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.73

    • Colesevelam

      Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .74 , 75 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.76 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.77

    • Colestipol

      Bile acid sequestrants, including colestipol, may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , K .78 , 79 People taking colestipol should consult with their doctor about vitamin malabsorption and supplementation. People should take other drugs and vitamin supplements one hour before or four to six hours after colestipol to improve absorption.80

      Animal studies suggest calcium and zinc may be depleted by taking cholestyramine, another bile acid sequestrant. 81 Whether these same interactions would occur with colestipol is not known.

    • Cycloserine

      Many antibiotics taken by mouth, including cycloserine, may kill friendly bacteria in the large intestine that produce vitamin K.82 With short-term (a few weeks or less) antibiotic use, the actions on vitamin K are usually mild and cause no problems. After antibiotic therapy is completed, vitamin K activity returns to normal.

    • Dexamethasone

      Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .83 The importance of these losses is unknown.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Isoniazid

      Many antibiotics taken by mouth, including isoniazid, may kill friendly bacteria in the large intestine that produce vitamin K.84 Vitamin K1 (phylloquinone) is now found in some multivitamins .

    • Meropenem

      Several cases of excessive bleeding have been reported in people who take antibiotics.85 , 86 , 87 , 88 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.89 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

    • Methotrexate
      Vitamin C combined with Vitamin K3 appears to increase the effectiveness of chemotherapy in animals.90
      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Mineral Oil

      Mineral oil has interfered with the absorption of many nutrients, including beta-carotene , calcium , phosphorus , potassium , and vitamins A , D , K , and E in some,91 but not all,92 research. Taking mineral oil on an empty stomach may reduce this interference. It makes sense to take a daily multivitamin-mineral supplement two hours before or after mineral oil. It is important to read labels, because many multivitamins do not contain vitamin K or contain inadequate (less than 100 mcg per day) amounts.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

    Reduce Side Effects

    • none

    Support Medicine

    • none

    Reduces Effectiveness

    • none

    Potential Negative Interaction

    • none

    Explanation Required

    • Amikacin

      Several cases of excessive bleeding have been reported in people who take antibiotics.93 , 94 , 95 , 96 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).97 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Amoxicillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.98 , 99 , 100 , 101 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.102 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Amoxicillin-Potassium Clavulanate

      Several cases of excessive bleeding have been reported in people who take antibiotics.103 , 104 , 105 , 106 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.107 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ampicillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.108 , 109 , 110 , 111 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.112 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ampicillin with Sulbactam

      Several cases of excessive bleeding have been reported in people who take antibiotics.113 , 114 , 115 , 116 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.117 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Azithromycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.118 , 119 , 120 , 121 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.122 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Aztreonam

      Several cases of excessive bleeding have been reported in people who take antibiotics.123 , 124 , 125 , 126 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.127 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Bacampicillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.128 , 129 , 130 , 131 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.132 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Bacitracin

      Several cases of excessive bleeding have been reported in people who take antibiotics.133 , 134 , 135 , 136 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).137 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Carbamazepine

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.138 Though some researchers recommend vitamin K supplementation prior to delivery,139 , 140 not all agree that supplementation for women taking anticonvulsant drugs is necessary.141 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

    • Cefaclor

      Several cases of excessive bleeding have been reported in people who take antibiotics.142 , 143 , 144 , 145 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.146 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefadroxil

      Several cases of excessive bleeding have been reported in people who take antibiotics.147 , 148 , 149 , 150 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.151 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefamandole

      Several cases of excessive bleeding have been reported in people who take antibiotics.152 , 153 , 154 , 155 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.156 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefazolin

      Several cases of excessive bleeding have been reported in people who take antibiotics.157 , 158 , 159 , 160 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.161 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefdinir

      Several cases of excessive bleeding have been reported in people who take antibiotics.162 , 163 , 164 , 165 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.166 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefepime

      Several cases of excessive bleeding have been reported in people who take antibiotics.167 , 168 , 169 , 170 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.171 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefixime

      Several cases of excessive bleeding have been reported in people who take antibiotics.172 , 173 , 174 , 175 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.176 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefonicid

      Several cases of excessive bleeding have been reported in people who take antibiotics.177 , 178 , 179 , 180 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.181 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefoperazone

      Several cases of excessive bleeding have been reported in people who take antibiotics.182 , 183 , 184 , 185 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.186 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefotaxime

      Several cases of excessive bleeding have been reported in people who take antibiotics.187 , 188 , 189 , 190 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.191 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefotetan

      Several cases of excessive bleeding have been reported in people who take antibiotics.192 , 193 , 194 , 195 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.196 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefoxitin

      Several cases of excessive bleeding have been reported in people who take antibiotics.197 , 198 , 199 , 200 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.201 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefpodoxime

      Several cases of excessive bleeding have been reported in people who take antibiotics.202 , 203 , 204 , 205 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.206 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cefprozil

      Several cases of excessive bleeding have been reported in people who take antibiotics.207 , 208 , 209 , 210 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.211 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ceftazidime

      Several cases of excessive bleeding have been reported in people who take antibiotics.212 , 213 , 214 , 215 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.216 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ciprofloxacin

      Several cases of excessive bleeding have been reported in people who take antibiotics.217 , 218 , 219 , 220 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.221 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cisplatin
      Vitamin C  combined with Vitamin K3 appears to increase the effectiveness of chemotherapy in animals. 222
      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Clarithromycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.223 , 224 , 225 , 226 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.227 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Clindamycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.228 , 229 , 230 , 231 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.232 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Cloxacillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.233 , 234 , 235 , 236 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.237 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Dapsone

      Several cases of excessive bleeding have been reported in people who take antibiotics.238 , 239 , 240 , 241 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.242 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Demeclocycline

      Several cases of excessive bleeding have been reported in people who take antibiotics.243 , 244 , 245 , 246 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.247 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Aditional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Dicloxacillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.248 , 249 , 250 , 251 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.252 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Doxycycline

      Several cases of excessive bleeding have been reported in people who take antibiotics.253 , 254 , 255 , 256 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.257 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Erythromycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.258 , 259 , 260 , 261 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.262 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Felbamate

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.263 Though some researchers recommend vitamin K supplementation prior to delivery,264 , 265 not all agree that supplementation for women taking anticonvulsant drugs is necessary.266 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

    • Gabapentin

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.267 Though some researchers recommend vitamin K supplementation prior to delivery,268 , 269 not all agree that supplementation for women taking anticonvulsant drugs is necessary.270 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Gentamicin

      Several cases of excessive bleeding have been reported in people who take antibiotics.271 , 272 , 273 , 274 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).275 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Levofloxacin

      Several cases of excessive bleeding have been reported in people who take antibiotics.276 , 277 , 278 , 279 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.280 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Methylprednisolone

      Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .281 The importance of these losses is unknown.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Mezlocillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.282 , 283 , 284 , 285 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.286 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Minocycline

      Several cases of excessive bleeding have been reported in people who take antibiotics.287 , 288 , 289 , 290 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.291 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Nafcillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.292 , 293 , 294 , 295 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.296 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Neomycin

      Neomycin can decrease absorption or increase elimination of many nutrients, including calcium , carbohydrates, beta-carotene , fats, folic acid , iron , magnesium , potassium , sodium, and vitamin A , vitamin B12 , vitamin D , and vitamin K .297 , 298 Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Netilmicin

      Several cases of excessive bleeding have been reported in people who take antibiotics.299 , 300 , 301 , 302 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).303 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Nitrofurantoin

      Several cases of excessive bleeding have been reported in people who take antibiotics.304 , 305 , 306 , 307 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.308 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ofloxacin

      Unlike with most other antibiotics, preliminary research suggests that people taking ofloxacin do not need to supplement vitamin K to protect against possible drug-induced depletion.309

    • Oxacillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.310 , 311 , 312 , 313 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.314 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Oxcarbazepine

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.315 Though some researchers recommend vitamin K supplementation prior to delivery,316 , 317 not all agree that supplementation for women taking anticonvulsant drugs is necessary.318 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

    • Penicillin V

      Several cases of excessive bleeding have been reported in people who take antibiotics.319 , 320 , 321 , 322 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.323 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Phenobarbital

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.324 Though some researchers recommend vitamin K supplementation prior to delivery,325 , 326 not all agree that supplementation for women taking anticonvulsant drugs is necessary.327 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Phenytoin

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.328 Though some researchers recommend vitamin K supplementation prior to delivery,329 , 330 not all agree that supplementation for women taking anticonvulsant drugs is necessary.331 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Piperacillin

      Several cases of excessive bleeding have been reported in people who take antibiotics.332 , 333 , 334 , 335 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.336 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Piperacillin-Tazobactam

      Several cases of excessive bleeding have been reported in people who take antibiotics.337 , 338 , 339 , 340 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.341 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Prednisolone

      Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .342 The importance of these losses is unknown.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Prednisone

      Oral corticosteroids have been found to increase urinary loss of vitamin K , vitamin C , selenium , and zinc .343 The importance of these losses is unknown.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Primidone

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.344 Though some researchers recommend vitamin K supplementation prior to delivery,345 , 346 not all agree that supplementation for women taking anticonvulsant drugs is necessary.347 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

    • Silver Sulfadiazine

      Several cases of excessive bleeding have been reported in people who take antibiotics.348 , 349 , 350 , 351 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.352 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Aditional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Streptomycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.353 , 354 , 355 , 356 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).357 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Sulfacetamide

      Several cases of excessive bleeding have been reported in people who take antibiotics.358 , 359 , 360 , 361 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.362 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Aditional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Sulfamethoxazole

      Several cases of excessive bleeding have been reported in people who take antibiotics.363 , 364 , 365 , 366 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.367 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Sulfanilamide

      Several cases of excessive bleeding have been reported in people who take antibiotics.368 , 369 , 370 , 371 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.372 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Aditional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Sulfasalazine

      Several cases of excessive bleeding have been reported in people who take antibiotics.373 , 374 , 375 , 376 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.377 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Sulfisoxazole

      Several cases of excessive bleeding have been reported in people who take antibiotics.378 , 379 , 380 , 381 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.382 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Aditional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Ticarcillin-Clavulanate

      Several cases of excessive bleeding have been reported in people who take antibiotics.383 , 384 , 385 , 386 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.387 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Tobramycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.388 , 389 , 390 , 391 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).392 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Topiramate

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.393 Though some researchers recommend vitamin K supplementation prior to delivery,394 , 395 not all agree that supplementation for women taking anticonvulsant drugs is necessary.396 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

    • Trimethoprim

      Several cases of excessive bleeding have been reported in people who take antibiotics.397 , 398 , 399 , 400 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.401 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Trimethoprim/ Sulfamethoxazole

      Several cases of excessive bleeding have been reported in people who take antibiotics.402 , 403 , 404 , 405 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.406 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Triple Sulfa

      Several cases of excessive bleeding have been reported in people who take antibiotics.407 , 408 , 409 , 410 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.411 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Aditional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Troleandomycin

      Several cases of excessive bleeding have been reported in people who take antibiotics.412 , 413 , 414 , 415 This side effect may result the killing of vitamin K-producing bacteria in the intenstines by the antibiotic. Risk factors for developing antibiotic-induced bleeding include being malnourished or having little or no oral intake (as in people undegoing major surgery or being treated in an intensive care unit).416 Infants may also be at increased risk, since vitamin K status in the first few months of life is often low. Little is known about which antibiotics do and do not promote vitamin K deficiency. People taking an antibiotic should discuss with their doctor the advisability of taking vitamin K.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Valproate

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.417 Though some researchers recommend vitamin K supplementation prior to delivery,418 , 419 not all agree that supplementation for women taking anticonvulsant drugs is necessary.420 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

      The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
    • Warfarin

      Warfarin slows blood clotting by interfering with vitamin K activity. Since vitamin K reverses the anticoagulant effects of warfarin,421 people taking warfarin should avoid vitamin K-containing supplements unless specifically directed otherwise by their prescribing doctor. Some vegetables (broccoli, Brussels sprouts, kale, parsley, spinach, and others) are high in vitamin K. Eating large quantities422 or making sudden changes in the amounts eaten of these vegetables can interfere with the effectiveness and safety of warfarin therapy. The greener the plant, the higher the vitamin K content.423 Other significant dietary sources of vitamin K include soybean oil, olive oil, cottonseed oil, and canola oil.424

      Vitamin K supplementation can be used, however, to counteract an overdose of warfarin.425 In addition, controlled and continuous supplementation with vitamin K (100 to 150 mcg per day) has been used effectively to reduce the fluctuations in dosage requirement that occur in some people taking warfarin or related drugs that have the same action as warfarin.426 , 427 , 428 Such treatment requires a doctor's supervision.

    • Zonisamide

      Some studies have shown that babies born to women taking anticonvulsant drugs have low blood levels of vitamin K, which might cause bleeding in the infant.429 Though some researchers recommend vitamin K supplementation prior to delivery,430 , 431 not all agree that supplementation for women taking anticonvulsant drugs is necessary.432 Until more information is available, pregnant women or women who might become pregnant while taking anticonvulsant drugs should discuss vitamin K supplementation with their healthcare practitioner.

    The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers' package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

    Side Effects

    Side Effects

    Allergic reactions to vitamin K injections have been reported on rare occasions.433

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    97. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    98. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    99. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    100. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    101. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    102. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    103. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    104. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    105. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    106. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    107. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    108. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    109. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    110. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    111. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    112. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    113. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    114. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    115. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    116. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    117. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    118. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    119. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    120. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    121. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    122. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    123. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    124. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    125. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    126. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    127. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    128. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    129. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    130. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    131. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    132. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    133. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    134. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    135. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    136. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    137. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    138. Cornelissen M, Steegers-Theunissen R, Kollee L, et al. Increased incidence of neonatal vitamin K deficiency resulting from maternal anticonvulsant therapy. Am J Obstet Gynecol 1993;168:923-8.

    139. Nulman I, Laslo D, Koren G. Treatment of epilepsy in pregnancy. Drugs 1999;57:535-44 [review].

    140. Cornelissen M, Steegers-Theunissen R, Kollee L, et al. Supplementation of vitamin K in pregnant women receiving anticonvulsant therapy prevents neonatal vitamin K deficiency. Am J Obstet Gynecol 1993;168:884-8.

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    143. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    144. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    145. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    146. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    147. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    148. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    149. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    150. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    151. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    152. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    153. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    154. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    155. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    156. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    157. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    158. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    159. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    160. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    161. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    162. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    163. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    164. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    165. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    166. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    167. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

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    169. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    170. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    171. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    172. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    173. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    174. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    175. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    176. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    177. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    178. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    179. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    180. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    181. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    182. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    183. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    184. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    185. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    186. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    187. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    188. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    189. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    190. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    191. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    192. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    193. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    194. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    195. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    196. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    197. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    198. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    199. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    200. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    201. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    202. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    203. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    204. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    205. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    206. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    207. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    208. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    209. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    210. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    211. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    212. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    213. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    214. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

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    217. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

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    220. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

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    224. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    225. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    226. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    227. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    228. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    229. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    230. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    231. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    232. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    233. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    234. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    235. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    236. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    237. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    238. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    239. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    240. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    241. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    242. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    243. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    244. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    245. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    246. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    247. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    248. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    249. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    250. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    251. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    252. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    253. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    254. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    255. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    256. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    257. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    258. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.

    259. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.

    260. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.

    261. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.

    262. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.

    263. Cornelissen M, Steegers-Theunissen R, Kollee L, et al. Increased incidence of neonatal vitamin K deficiency resulting from maternal anticonvulsant therapy. Am J Obstet Gynecol 1993;168:923-8.

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