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What Is High Blood Pressure?

High blood pressure (HBP) is a serious condition that can lead to coronary heart disease, heart failure, stroke, kidney failure, and other health problems.

"Blood pressure" is the force of blood pushing against the walls of the arteries as the heart pumps blood. If this pressure rises and stays high over time, it can damage the body in many ways.

Overview

About 1 in 3 adults in the United States has HBP. The condition itself usually has no signs or symptoms. You can have it for years without knowing it. During this time, though, HBP can damage your heart, blood vessels, kidneys, and other parts of your body.

Knowing your blood pressure numbers is important, even when you're feeling fine. If your blood pressure is normal, you can work with your health care team to keep it that way. If your blood pressure is too high, treatment may help prevent damage to your body's organs.

Blood Pressure Numbers

Blood pressure is measured as systolic (sis-TOL-ik) and diastolic (di-ah-STOL-ik) pressures. "Systolic" refers to blood pressure when the heart beats while pumping blood. "Diastolic" refers to blood pressure when the heart is at rest between beats.

You most often will see blood pressure numbers written with the systolic number above or before the diastolic number, such as 120/80 mmHg. (The mmHg is millimeters of mercury—the units used to measure blood pressure.)

The table below shows normal blood pressure numbers for adults. It also shows which numbers put you at greater risk for health problems.

Categories for Blood Pressure Levels in Adults (measured in millimeters of mercury, or mmHg)

Category Systolic
(top number)
  Diastolic
(bottom number)
Normal Less than 120 And Less than 80
Prehypertension 120–139 Or 80–89
High blood pressure      
     Stage 1 140–159 Or 90–99
     Stage 2 160 or higher Or 100 or higher

The ranges in the table apply to most adults (aged 18 and older) who don't have short-term serious illnesses.

Blood pressure doesn't stay the same all the time. It lowers as you sleep and rises when you wake up. Blood pressure also rises when you're excited, nervous, or active. If your numbers stay above normal most of the time, you're at risk for health problems. The risk grows as blood pressure numbers rise. "Prehypertension" means you may end up with HBP, unless you take steps to prevent it.

If you're being treated for HBP and have repeat readings in the normal range, your blood pressure is under control. However, you still have the condition. You should see your doctor and follow your treatment plan to keep your blood pressure under control.

Your systolic and diastolic numbers may not be in the same blood pressure category. In this case, the more severe category is the one you're in. For example, if your systolic number is 160 and your diastolic number is 80, you have stage 2 HBP. If your systolic number is 120 and your diastolic number is 95, you have stage 1 HBP.

If you have diabetes or chronic kidney disease, HBP is defined as 130/80 mmHg or higher. HBP numbers also differ for children and teens. (For more information, go to "How Is High Blood Pressure Diagnosed?")

Outlook

Blood pressure tends to rise with age. Following a healthy lifestyle helps some people delay or prevent this rise in blood pressure.

People who have HBP can take steps to control it and reduce their risk for related health problems. Key steps include following a healthy lifestyle, having ongoing medical care, and following your treatment plan.

This image focuses on high blood pressure in women and explains how high blood pressure increases your risk for heart disease. An estimated 1 in 3 women has high blood pressure, and the condition is dangerous because it often causes no symptoms. The image also contains a chart showing ranges of blood pressure numbers for normal blood pressure, prehypertension, stage 1 hypertension, and stage 2 hypertension.

The image focuses on high blood pressure in women and explains how high blood pressure increases the risk of heart disease. An estimated 1 in 3 women has high blood pressure, and the condition is dangerous because it often causes no symptoms.

The image also contains a chart showing ranges of blood pressure numbers for normal blood pressure, prehypertension, stage 1 hypertension, and stage 2 hypertension (also discussed in the text chart earlier in this section). Finally, the image states that you can take action to prevent high blood pressure by reducing sodium (salt) intake. Most adults should have less than one teaspoon, or 2,300  milligrams, of sodium a day. Being active and maintaining a healthy weight also can help you prevent high blood pressure.

Sources: National Center for Health Statistics. (2007–2010). National Health and Nutrition Examination Survey; Centers for Disease Control and Prevention. (2011). Vital signs: prevalence, treatment, and control of hypertension, 1999–2002 and 2005–2008. MMWR: Morbidity & Mortality Weekly Report, 60(4), 103–108; National Heart, Lung, and Blood Institute, National High Blood Pressure Education Program. (2004). The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.

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August 2, 2012