When to Worry About a Child's Fever

Nearly every parent has felt their child’s hot, feverish forehead and worried. Is it serious? How high is too high? Should they go to the doctor?

Cara Barone, M.D., a pediatrician at the Palo Alto Medical Foundation, often sees worried parents bring in their feverish children for treatment. When it comes to fever, she explains, prompt medical treatment is sometimes very important. However, in most cases, fevers are not dangerous and can even be viewed as helpful as they fight infections naturally.

“It’s important to know when to treat, and when to let nature take its course,” she says.

Causes of Fever

Fever is a healthy sign the body is working properly to fight and overcome an infection, Dr. Barone explains. Through a chemical reaction, your body elevates your core temperature in an effort to stop bad viruses and bacteria from replicating. Since viruses and bacteria can normally only reproduce when conditions are just right, this is a very effective way to shut them down.

The most common sources of infection in children are viruses. Young children may have seven to 10 viral illnesses with fever each year – especially if they are in daycare or preschool, where viruses spread easily among children. The second most common sources of infection are bacteria. Both types of infections, viral and bacterial, can cause fevers.

“We worry most about fevers in very young children – especially infants less than 3 months old – because their immune systems are still developing,” Dr. Barone says. “This leaves them at risk for severe infections.”

For preschoolers and school-age children, pediatricians worry much less about fevers unless the fever lasts for four days or more and causes symptoms such as significant listlessness/irritability, a bad sore throat, worsening coughing or pain with urination.

The Right Way to Take a Temperature

One of the most important skills of parenting is to know how to take a temperature correctly. In babies and children less than 1 year of age, it is important to feel comfortable taking a rectal temperature.

“This is by far the most accurate method of taking a young child’s temperature,” Dr. Barone says. “New parents are often frightened to take a rectal temperature, but it doesn’t hurt their baby and it’s quite simple once you know how to do it.”

To take a rectal temperature, lubricate the digital thermometer with petroleum jelly and insert the silver tip of the thermometer into your baby’s rectum about one-quarter of an inch to one-half of an inch. Hold it gently for one minute, then remove and read the temperature. The American Academy of Pediatrics has illustrations demonstrating how to take a rectal temperature at healthychildren.org.

For children older than 1 year of age, the best and most accurate methods of taking a temperature are with an oral digital thermometer or a tympanic (ear) thermometer. “Ear thermometers are great for toddlers,” Dr. Barone says. “They are usually accurate, but can be off if your child has lots of ear wax.”

To increase your odds of getting an accurate temperature reading with an ear thermometer, study the illustrations showing how to use one at healthychildren.org.

When to See a Doctor

In infants less than 2 months of age, a fever is any temperature over 100.4 degrees (all temperatures in this article are in Fahrenheit). It’s also a concern if your newborn’s temperature is less than 96 degrees F. For an abnormal temperature in your newborn, call your doctor or go to the urgent care clinic or emergency room — your newborn needs to be seen right away.

In babies and children older than 3 months, a fever is a temperature greater than 101.5 degrees F. Call your doctor if your child’s temperature reaches 102.2 degrees F or higher.

Most fevers go away in a couple of days. Call your doctor if the fever lasts four days or more. Call the doctor right away if your feverish child has vomiting or diarrhea, earache, severe abdominal pain, headache, stiff neck, sore throat, trouble breathing, pain when urinating, swollen joints, other localized pain and a purplish/dark rash that does not fade when you press on it. Also call the doctor if your child is listless or refuses to drink fluids.

When to Use Fever Relievers

Fever-reducing medicines are not needed for low-grade fevers (99 to 101 degrees F) unless your child seems uncomfortable or is not drinking well.

“Once children’s fevers rise above 101.5 degrees F, they generally feel miserable, and fever-reducing medicines will help them feel better,” Dr. Barone says. “Children may be more likely to drink fluids properly after they have had fever-reducing medicines.”

It is important to make sure you are giving your child the correct dose of medicine. Too little medicine won’t be effective, but too much could be dangerous. Follow the instructions on the label carefully and only use the cup or syringe that came with that medicine. (Never use a household teaspoon. They vary in size, so your dose may be wrong.)

Child-Safe Fever Medicines

Two types of fever medicine are safe for children: acetaminophen (sold as Tylenol) and ibuprofen (sold as Motrin and Advil).

Tylenol is the only fever-reducing medicine approved by the Food and Drug Administration for babies younger than 6 months old. Motrin has a few advantages over Tylenol for children older than 6 months of age:

• It lasts between six and eight hours.
• It can reduce swelling from teething and ear infections with its anti-inflammatory properties.
• It may be a better choice for children who have asthma or recurrent wheezing.

It’s a good idea to print out the correct dosing for these medicines. Or bookmark the pages from the American Academy of Pediatrics for easy reference:

• Tylenol (acetaminophen) dosing chart
• Motrin and Advil (ibuprofen) dosing chart

“Although fevers can be frightening, remember that they are a sign of a healthy immune system,” Dr. Barone says. “If your child has a low fever and no other worrisome symptoms, provide plenty of fluids, rest and love. The fever should go away in a few days.”