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Understanding High Blood Pressure

+ Enlarge At your next medical checkup, when your health care provider puts a cuff around your arm to take your blood pressure, be sure to ask about your numbers.

Did you know that your blood pressure can be a good indicator of your heart’s health?

High blood pressure is actually a leading risk factor for heart disease and early death. It’s sometimes called the “silent killer” because many people don’t know they have it, yet it can do a lot of harm.

If you already have high blood pressure, the good news is that even small reductions in your blood pressure can help protect your cardiovascular health, and as a result help prevent heart attacks, stroke, heart failure and chronic kidney disease.

What is blood pressure?

Blood pressure is a measure of how hard your blood pushes against your arteries as it moves through your body.

Blood pressure rises and falls naturally during the day. But if it stays too high, over time it can lead to health problems. High blood pressure is also called hypertension.

Facts About High Blood Pressure

  • Nearly 1 in 3 American adults has high blood pressure.
  • About 1 in 5 adults don’t know they have it.
  • Half do not have their blood pressure under control.
  • It’s one of the top risk factors associated with heart disease and stroke—which together are the leading cause of death—and chronic kidney disease.
  • It is usually very treatable.

Why knowing your blood pressure matters

Blood pressure can affect your body in many ways. Untreated, high blood pressure increases the strain on the heart and arteries, and it can eventually lead to: 

  • blood vessel damage (atherosclerosis)
  • heart attack
  • stroke
  • heart failure
  • kidney failure
  • eye damage

Often, there may be no signs or symptoms that tell you when your blood pressure is too high. Not surprisingly, the higher it is, the more likely you are to have these problems. The good news: High blood pressure can be treated or even prevented.

What do your numbers mean?

Blood pressure is given as two numbers. You’ve probably heard your health care provider say something like “130 over 70.” So what do these numbers mean?

Systolic, the top number, is the pressure or force in the arteries when the heart pumps. When the heart contracts, the pressure in the arteries rises.
Diastolic, the bottom number, is the pressure in the vessels when the heart relaxes between heartbeats.

These numbers are measured in millimeters of mercury (mmHg). Hypertension then is blood pressure that is above 140 mmHg systolic (higher value) and/or above 90 mmHg diastolic (lower value). You can have high blood pressure even if just one of the numbers is above what it should be.

Blood Pressure Classifications

  Systolic BP mmHg
  Diastolic BP mmHg
 <120  AND
Prehypertension  120-139  OR  80-89
 ≥140  OR  ≥90
Source: Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, NHLBI


Even if your blood pressure is only slightly elevated, you need to take it seriously. Blood pressure measures that are close to the cut off for having hypertension can serve as an early warning sign or red flag that it’s time to step up efforts to prevent high blood pressure. Prehypertension is increasingly linked to health issues, even stroke.

Talk with your health care team about learning how to check and track your blood pressure over time.

How do I know if I am at risk?

Some things can make high blood pressure more likely. For example:

  • being older /getting older (as we age, blood vessels get stiffer)
  • being very overweight
  • drinking too much alcohol
  • having a family history of high blood pressure
  • eating too much salt
  • having diabetes
  • smoking
  • experiencing prolonged stress
  • in some cases, having low levels of potassium in your diet
  • being African-American

Other health conditions such as sleep apnea, chronic kidney disease and pre-eclampsia (high blood pressure during pregnancy) can trigger high blood pressure. Certain medications can also cause your blood pressure to rise; for example, some diet pills and cold medicines. If you have high blood pressure, your health care provider should consider and rule out other possible causes.

African-Americans are also more prone to having high blood pressure, and may respond differently to medications.

< Back to Blood Pressure Home Signs and Symptoms >

Published: June 2016
Medical Reviewers: Martha Gulati, MD, MS, FACC, FAHA; Keith C. Ferdinand, MD, FACC, FAHA; John D. Bisognano, MD, PhD, FACC


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