Blood pressure is a measurement of the force exerted against the walls of your arteries as your heart pumps blood to your body. Hypertension is the term used to describe high blood pressure.
Blood pressure readings are given as two numbers. The top number is called the systolic blood pressure. The bottom number is called the diastolic blood pressure. For example, 120 over 80 (written as 120/80 mm Hg).
One or both of these numbers can be too high. (Note: These numbers apply to people who are not taking medicines for blood pressure and are not ill.)
- Normal blood pressure is when your blood pressure is lower than 120/80 mm Hg most of the time.
- High blood pressure (hypertension) is when your blood pressure is 140/90 mm Hg or above most of the time.
- If your blood pressure numbers are 120/80 or higher, but below 140/90, it is called pre-hypertension.
If you have heart or kidney problems, or you had a stroke, your doctor may want your blood pressure to be even lower than that of people who do not have these conditions.
Many factors can affect blood pressure, including:
- The amount of water and salt you have in your body
- The condition of your kidneys, nervous system, or blood vessels
- Your hormone levels
You are more likely to be told your blood pressure is too high as you get older. This is because your blood vessels become stiffer as you age. When that happens, your blood pressure goes up. High blood pressure increases your chance of having a stroke, heart attack, heart failure, kidney disease, or early death.
You have a higher risk of high blood pressure if you:
- Are African American
- Are obese
- Are often stressed or anxious
- Drink too much alcohol (more than 1 drink per day for women and more than 2 drinks per day for men)
- Eat too much salt
- Have a family history of high blood pressure
- Have diabetes
Most of the time, no cause of high blood pressure is found. This is called essential hypertension.
High blood pressure that is caused by another medical condition or medicine you are taking is called secondary hypertension. Secondary hypertension may be due to:
- Chronic kidney disease
- Disorders of the adrenal gland (such as pheochromocytoma or Cushing syndrome)
- Pregnancy or preeclampsia
- Medicines such as birth control pills, diet pills, some cold medicines, and migraine medicines
- Narrowed artery that supplies blood to the kidney (renal artery stenosis)