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High Blood Pressure (Hypertension)

Harvard Health Publications

Blood pressure has two components:

  • Systolic pressure is the top number. It represents the pressure the heart generates when it beats to pump blood to the rest of the body.

  • Diastolic pressure is the bottom number. It refers to the pressure in the blood vessels between heartbeats.

Blood pressure is measured in millimeters of mercury (mm Hg). So blood pressure would be expressed, for example, as 120/80 mm Hg.

High blood pressure is diagnosed when one or both of these numbers is too high. High blood pressure is also called hypertension.

For decades, high blood pressure was defined as 140/90 mm Hg. In November, 2017, new United States guidelines lowered the threshold for diagnosing the condition. According to new guidelines, anyone with a reading of 130/80 mm Hg or higher has blood pressure. Based on this new definition, nearly half of Americans now fall into this group.

Blood pressure is now categorized as follows:

Normal: Less than 120/80 mm Hg

Elevated: 120/80 to 129/79 mm Hg

Stage 1 hypertension: 130/80 to 139/89 mm Hg

Stage 2 hypertension: 140/90 mm Hg and above

Although high blood pressure can cause symptoms such as headache and pounding heartbeat, it often causes no symptoms at all.

So why worry about high blood pressure? Because even when high blood pressure is not causing any symptoms, it can silently damage many organs, including the:

  • Brain

  • Eyes

  • Heart

  • Kidneys

  • Arteries throughout the body

You may not recognize the damage that silent hypertension has been doing to your body until you suddenly are stricken with a major disease. For example, hypertension increases your risk of heart attack, stroke, and kidney failure.

High Blood Pressure (Hypertension)


Usually, hypertension does not directly cause symptoms. When blood pressure is very high, it can cause:

  • Headaches

  • Dizziness

  • Fatigue

  • Ringing in the ears


The diagnosis of hypertension depends on blood pressure readings. Therefore, it's essential that blood pressure be measured carefully.

To obtain an accurate blood pressure measurement:

  • Avoid the following for at least one hour before you have your blood pressure taken:

  • Strenuous exercise

  • Smoking

  • Eating

  • Drinking caffeinated beverages

  • Be seated for at least five minutes before the reading is taken.

  • Do not talk while your blood pressure is being measured.

  • Two readings should be recorded and averaged.

If your blood pressure is high, your doctor should examine your eyes, heart, and nervous system, to look for evidence of damage from hypertension.

If there is no such evidence, you should return for at least two more blood pressure measurements. Only then should the doctor diagnose you with hypertension. That is because a single high reading can happen to anyone.

If you are diagnosed with hypertension, other tests will check for organ damage. These tests can include:

  • Blood tests to check kidney function

  • An electrocardiogram (EKG) to look for:

  • Thickening of the heart muscle

  • Irregular heart rhythms

  • A chest x-ray to look for:

  • Enlargement of the heart

  • Fluid buildup in the lungs due to heart failure


To prevent high blood pressure:

  • Get regular aerobic exercise

  • Limit your intake of salt and alcoholic beverages

  • Eat a diet rich in fruits and vegetables and low in saturated fats

  • Avoid smoking

  • Maintain a desirable body weight

Hypertension increases your risk of heart attack and stroke. So it is important to modify your risk factors for coronary artery disease. In addition to the above actions, you should:

  • Quit smoking

  • Reduce your high LDL (bad) cholesterol

You may be able to cure your hypertension with lifestyle changes alone. Simply changing what you eat and drink can bring down systolic blood pressure by as much as 11 points, according to some estimates.


Elevated blood pressure. If your blood pressure is simply elevated, meaning the first number (systolic blood pressure) falls in the range of 120 to 129 while the second number (diastolic blood pressure) remains below 80, medication is not recommended. Instead, you should focus on healthy lifestyle changes:

  • A diet high in fruits and vegetables

  • Less salt and saturated fats

  • More activity

  • Weight loss if you’re overweight

  • Limiting your alcohol to moderate amounts

Stage 1 hypertension. You have stage 1 hypertension if your systolic blood pressure is 130 to 139, your diastolic pressure is 80 to 89, or both. Even if your systolic blood pressure hovers above 130, you still may not need medication immediately. Your doctor may suggest a trial of lifestyle changes first if you don’t have heart disease and you have a low risk of developing it over the next 10 years. But many people find that they need to take some type of medication in order to reduce their blood pressure numbers to healthier levels.

Stage 2 hypertension. You have stage 2 hypertension if your systolic pressure is at least 140 mm Hg, your diastolic pressure is at least 90 mm Hg, or both. In addition to lifestyle modifications, you will likely need to start medication to lower your blood pressure. That doesn’t mean you will always need drug therapy. Losing weight, decreasing stress, eating healthier, and exercising daily can potentially bring your readings into the normal range. But even if you still need medication, your lifestyle efforts help prevent you from needing higher drug doses in the future.

Antihypertensive medications include:

  • Diuretics

  • Beta-blockers

  • ACE inhibitors

  • Angiotensin-receptor blockers

  • Calcium channel blockers

  • Alpha blockers

People with diabetes, kidney disease or heart problems are at higher risk of complications from hypertension. As a result, they are usually treated more aggressively with medications.

When To Call A Professional

Adults should have their blood pressure measured at least every few years.

If your blood pressure is 120/80 mm Hg or higher, schedule regular appointments with your doctor. Have your blood pressure monitored more regularly. And get advice about modifying your lifestyle to prevent future problems.


The prognosis for hypertension depends on:

  • How long you've had it

  • How severe it is

  • If you have other conditions (such as diabetes) that increase the risk of complications

Hypertension can lead to a poor prognosis even if you do not have symptoms.

When high blood pressure is treated adequately, the prognosis is much better. Both lifestyle changes and medicines can control your blood pressure.

External resources

American Heart Association (AHA)7272 Greenville Ave.Dallas, TX 75231Toll-Free: (800) 242-8721

National Heart, Lung, and Blood Institute (NHLBI)P.O. Box 30105Bethesda, MD 20824-0105Phone: (301) 592-8573TTY: (240) 629-3255Fax: (301) 592-8563

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