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What is High Blood Pressure?

Blood pressure is the force of blood 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. Knowing your blood pressure numbers is important, even when you are feeling fine. High blood pressure – also called HBP –  usually has no symptoms. You can have it for years without knowing it. During this time, though, HBP can damage your:

  • heart
  • blood vessels
  • kidneys
  • other parts of your body. 

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-a-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 do not have short-term serious illnesses.

Blood pressure does not stay the same all the time. It lowers as you sleep and rises when you wake up. Blood pressure also rises when you are:

  • excited
  • nervous
  • or active.

If your numbers stay above normal most of the time, you are at risk for health problems.

All levels above 120/80 mmHg raise your risk, and the risk grows as blood pressure numbers rise. “Prehypertension” means you are likely to end up with HBP, unless you take steps to prevent it.

If you are 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 are 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. 



Blood pressure tends to rise with age. Following a healthy lifestyle helps some people delay or prevent this rise in blood pressure.  If you have HBP, you can take steps to control it and reduce your risk of related health problems. Key steps you can take include:

  • following a healthy lifestyle
  • having ongoing medical care
  • following your treatment plan.


Source: What is High Blood Pressure? National Heart, Lung and Blood Institute

For more information:

Go to the High Blood Pressure health topic.