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High blood pressure is a blood pressure reading of 140/90 mmHg or higher. Both numbers are important. About one in every four American adults has high blood pressure. Once high blood pressure develops, it usually lasts a lifetime. The good news is that it can be treated and controlled. High blood pressure is called "the silent killer" because it usually has no symptoms. Some people may not find out they have it until they have trouble with their heart, brain, or kidneys. When high blood pressure is not found and treated, it can cause:
  • The heart to get larger, which may lead to heart failure.

  • Small bulges (aneurysms) to form in blood vessels. Common locations are the main artery from the heart (aorta), arteries in the brain, legs, and intestines, and the artery leading to the spleen.

  • Blood vessels in the kidney to narrow, which may cause kidney failure.

  • Arteries throughout the body to "harden" faster, especially those in the heart, brain, kidneys, and legs. This can cause a heart attack, stroke, kidney failure, or amputation of part of the leg.

  • Blood vessels in the eyes to burst or bleed, which may cause vision changes and can result in blindness.

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What Is High Blood Pressure?

Blood is carried from the heart to all parts of your body in vessels called arteries. Blood pressure is the force of the blood pushing against the walls of the arteries. Each time the heart beats (about 60-70 times a minute at rest), it pumps out blood into the arteries. Your blood pressure is at its highest when the heart beats, pumping the blood. This is called systolic pressure. When the heart is at rest, between beats, your blood pressure falls. This is the diastolic pressure. Blood pressure is always given as these two numbers, the systolic and diastolic pressures. Both are important. Usually they are written one above or before the other, such as 120/80 mmHg. The top number is the systolic and the bottom the diastolic. When the two measurements are written down, the systolic pressure is the first or top number, and the diastolic pressure is the second or bottom number (for example, 120/80). If your blood pressure is 120/80, you say that it is "120 over 80." Blood pressure changes during the day. It is lowest as you sleep and rises when you get up. It also can rise when you are excited, nervous, or active. Still, for most of your waking hours, your blood pressure stays pretty much the same when you are sitting or standing still. That level should be lower than 120/80. When the level stays high, 140/90 or higher, you have high blood pressure. With high blood pressure, the heart works harder, your arteries take a beating, and your chances of a stroke, heart attack, and kidney problems are greater.

What is normal blood pressure?

A blood pressure reading below 120/80 is considered normal. In general, lower is better. However, very low blood pressures can sometimes be a cause for concern and should be checked out by a doctor. Doctors classify blood pressures under 140/90 as either "normal," or "prehypertension."

  • "Normal" blood pressures are lower than 120/80.
  • "Prehypertension" is blood pressure between 120 and 139 for the top number, or between 80 and 89 for the bottom number. For example, blood pressure readings of 138/82, 128/89, or 130/86 are all in the "prehypertension" range. If your blood pressure is in the prehypertension range, it is more likely that you will end up with high blood pressure unless you take action to prevent it.

What is high blood pressure?

A blood pressure of 140/90 or higher is considered high blood pressure. Both numbers are important. If one or both numbers are usually high, you have high blood pressure. If you are being treated for high blood pressure, you still have high blood pressure even if you have repeated readings in the normal range. There are two levels of high blood pressure: Stage 1 and Stage 2 (see the chart below). Categories for Blood Pressure Levels in Adults*
(In mmHg, millimeters of mercury)
Category Systolic
(Top number)
(Bottom number)
Normal Less than 120 Less than 80
Prehypertension 120-139 80-89
High Blood Pressure Systolic Diastolic
Stage 1 140-159 90-99
Stage 2 160 or higher 100 or higher
* For adults 18 and older who:
  • Are not on medicine for high blood pressure
  • Are not having a short-term serious illness
  • Do not have other conditions such as diabetes and kidney disease

Note: When systolic and diastolic blood pressures fall into different categories, the higher category should be used to classify blood pressure level. For example, 160/80 would be stage 2 high blood pressure.
There is an exception to the above definition of high blood pressure. A blood pressure of 130/80 or higher is considered high blood pressure in persons with diabetes and chronic kidney disease.

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What Causes High Blood Pressure?

In many people with high blood pressure, a single specific cause is not known. This is called essential or primary high blood pressure. Research is continuing to find causes. In some people, high blood pressure is the result of another medical problem or medication. When the cause is known, this is called secondary high blood pressure.

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Who Gets High Blood Pressure?

More than 50 million American adults--1 in 4--have high blood pressure. In the U.S., high blood pressure occurs more often in African Americans. Compared to other groups, blacks:

  • Tend to get high blood pressure earlier in life
  • Usually have more severe high blood pressures
  • Have a higher death rate from stroke, heart disease, and kidney failure.
Many people get high blood pressure as they get older. Over half of all Americans age 60 and older have high blood pressure. This is not a part of healthy aging! There are things you can do to help keep your blood pressure normal, such as eating a healthy diet and getting more exercise. Your chances of getting high blood pressure are also higher if you:
  • Are overweight
  • Are a man over the age of 45
  • Are a woman over the age of 55
  • Have a family history of high blood pressure
  • Have a "prehypertension (120-139/80-89)"
Other things that can raise blood pressure include:
  • Eating too much salt
  • Drinking too much alcohol
  • Not eating enough potassium
  • Not exercising
  • Taking certain medicines
  • Stress that is long-lasting

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Older Adults and High Blood Pressure

A common form of high blood pressure in older adults is isolated systolic hypertension (ISH). ISH is high blood pressure, but only the top (systolic) number is high (140 or higher). ISH can be as harmful as high blood pressure in which both numbers are high. ISH is the most common form of high blood pressure for older Americans. About 2 out of 3 people over age 60 with high blood pressure have ISH. You may have ISH and feel fine. As with other types of high blood pressure, ISH often causes no symptoms. To find out if you have ISH--or any type of high blood pressure--get your blood pressure checked. If not treated, ISH can cause damage to your arteries and to body organs. ISH is treated the same way as high blood pressure in which both systolic and diastolic pressures are high: by making changes in your health habits and with blood pressure medicines, if needed.

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Signs and Symptoms of High Blood Pressure

High blood pressure is called "the silent killer" because you can have it for years without knowing it. The only way to find out if you have high blood pressure is to have your blood pressure measured. Using a blood pressure cuff and stethoscope or electronic sensor, your doctor or nurse can take your blood pressure and tell you if it is high. Even though high blood pressure usually has no signs or symptoms, it is dangerous if it continues over time. It is important to find out if you have high blood pressure and, if so, to keep it under control.

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How is High Blood Pressure Treated?

Usually, the goal is to keep your blood pressure below 140/90 (130/80 if you have diabetes or chronic kidney disease). Ask your doctor what your blood pressure goal should be. Some people can prevent or control high blood pressure by changing to healthier habits, such as:

  • Eating healthy foods that include fruits, vegetables, and low-fat dairy products
  • Cutting down on salt and sodium in the diet
  • Losing excess weight and staying at a healthy weight
  • Staying physically active (for example, walking 30 minutes a day)
  • Limiting alcohol intake.
Sometimes blood pressure stays too high even when a person makes these kinds of healthy changes. In that case, it is necessary to add medicine to help lower blood pressure. Medicines will control your blood pressure but they cannot cure it. You will need to take high blood pressure medicine for a long time. Blood pressure medicines work in different ways to lower blood pressure. Often, two or more drugs work better than one. Some drugs lower blood pressure by removing extra fluid and salt from your body. Others affect blood pressure by slowing down the heartbeat, or by relaxing and widening blood vessels. Below are the types of medicines used to treat high blood pressure:
  • Diuretics are sometimes called "water pills." They work by helping your kidneys flush excess water and salt from your body. This reduces the amount of fluid in your blood, and your blood pressure goes down. There are different types of diuretics. They are often used along with other high blood pressure medicines and may be combined with another medicine in one pill.
  • Beta blockers help your heart beat slower and with less force. Your heart pumps less blood through the blood vessels, and your blood pressure goes down.
  • Angiotensin converting enzyme (ACE) inhibitors keep your body from making a hormone called angiotensin II, which normally causes blood vessels to narrow. ACE inhibitors prevents this narrowing so your blood pressure goes down.
  • Angiotensin II Receptor Blockers (ARBS) are newer blood pressure drugs that protect your blood vessels from angiotensin II. As a result, the blood vessels relax and become wider, and your blood pressure goes down.
  • Calcium channel blockers (CCBs) keep calcium from entering the muscle cells of your heart and blood vessels. This causes blood vessels to relax, and your blood pressure goes down.
  • Alpha blockers reduce nerve impulses that tighten blood vessels, allowing blood to pass more easily and causing blood pressure to go down.
  • Alpha-beta blockers reduce nerve impulses to blood vessels the same way alpha blockers do, but they also slow the heartbeat, as beta blockers do. As a result, blood pressure goes down.
  • Nervous system inhibitors relax blood vessels by controlling nerve impulses from the brain. This causes blood vessels to become wider and blood pressure to go down.
  • Vasodilators open blood vessels by directly relaxing the muscle in the vessel walls, causing blood pressure to go down.
It is important that you take your blood pressure medication the same time each day. The NHLBI Web site, Your Guide to Lowering Your High Blood Pressure, offers tips to help you remember to take your blood pressure medications

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How Do You Know if You Have High Blood Pressure?

Only your doctor can tell you if you have high blood pressure. Most doctors will check your blood pressure several times on different days before deciding that you have high blood pressure. A diagnosis of high blood pressure is given if repeated readings are 140/90 or higher or 130/80 or higher if you have diabetes or chronic kidney disease. Having your blood pressure tested is quick and easy. Your doctor or nurse will use some type of a gauge, a stethoscope (or electronic sensor), and a blood pressure cuff, also called a sphygmomanometer(sfig-mo-ma-NOM-e-ter). Blood pressure readings are usually taken when you are sitting or lying down and relaxed. Below are things you can do before going to get your blood pressure taken:

  • Do not drink coffee or smoke cigarettes 30 minutes before having your blood pressure taken.
  • Wear short sleeves.
  • Go to the bathroom before the reading. Having a full bladder can change your blood pressure reading.
  • Sit for 5 minutes before the test.
You should ask the doctor or nurse to tell you the blood pressure reading in numbers. You also can check your blood pressure at home with a home blood pressure measurement device, or monitor. It is important that you understand how to use the monitor properly. Your doctor, nurse, or pharmacist can help you check the monitor and teach you how to use it correctly. You also may ask for their help in choosing the right blood pressure monitor for you. Blood pressure monitors can be bought at discount chain stores and pharmacies. Below are additional things to do when taking your blood pressure at home:
  • Sit with your back supported and your feet flat on the floor.
  • Rest your arm on a table at the level of your heart.
  • Take two readings, at least 2 minutes apart, and average the results.
Some people's blood pressure is high only when they visit the doctor's office. This condition is called "white coat" hypertension. If your doctor suspects this, you may be asked to check and record your blood pressure at home with a home monitor. Another way to check blood pressure away from the doctor's office is by using an ambulatory blood pressure monitor. This device is worn for 24 hours and can take blood pressure every 30 minutes.

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How Can I Prevent High Blood Pressure?

You can take steps to prevent high blood pressure. These steps include:

  • Keeping a healthy weight
  • Being physically active
  • Following a healthy eating plan that emphasizes fruits, vegetables, and low-fat dairy foods. Also see the DASH diet
  • Choosing and preparing foods with less salt and sodium
  • Drinking alcohol in moderation if you drink.

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