When you have high blood pressure , or hypertension, the force of blood against your artery walls is too strong. High blood pressure can damage your arteries, heart, and kidneys, and lead to atherosclerosis and stroke . Hypertension is called a "silent killer'' because it does not cause symptoms unless it is severely high and, without your knowing it, causes major organ damage if not treated.

Your blood pressure measurement consists of two numbers: systolic and diastolic.

• The systolic measurement is the pressure of blood against your artery walls when the heart has just finished pumping (contracting). It is the first or top number of a blood pressure reading.
• The diastolic measurement is the pressure of blood against your artery walls between heartbeats, when the heart is relaxed and filling with blood. It is the second or bottom number in a blood pressure reading.

People with borderline, or "high-normal," blood pressure have a higher risk of developing high blood pressure. A new study has shown that they also have a higher risk for heart disease than those with optimal blood pressure (less than 120/80 millimeters of mercury [mm Hg]). ¹

What causes high blood pressure?

In most cases, a doctor may not be able to pinpoint the exact cause of your high blood pressure. But several factors are known to increase blood pressure, including obesity, heavy alcohol use, family history of high blood pressure, high salt intake, and aging. A sedentary lifestyle, stress, low potassium intake, low calcium intake, and resistance to insulin may also cause your blood pressure to rise. If one or more of these factors is causing your high blood pressure, you have primary, or essential, high blood pressure, which is the most common type.

Secondary high blood pressure is caused by certain medications or other conditions, such as pregnancy or narrowing of the kidney arteries.

Labile hypertension is blood pressure that changes rapidly, often in response to stress or activity. This type of high blood pressure is most common in younger people.

Elevated blood pressure readings may not always mean you have high blood pressure. For some people, just being in a medical setting causes their blood pressure to rise. This is called white-coat hypertension .

Malignant hypertension ( hypertensive crisis ) is high blood pressure that increases rapidly. The cause may be unknown or may be due to medication or another condition.

Isolated systolic high blood pressure is when systolic blood pressure is elevated above 140 mm Hg, but diastolic blood pressure stays within the normal range of less than 90 mm Hg. This type of high blood pressure is more common in older adults, especially older women.

Are there risk factors that make it more likely I will develop high blood pressure?

Several factors increase your risk for developing high blood pressure. Some of them, such as salt intake and alcohol consumption, are lifestyle issues that you can control. Other factors, such as your family history, are not controllable.

Risk factors for primary (essential) high blood pressure include:

• A family history of high blood pressure.
• Aging.
• Black race.
• Sodium (salt) intake.
• Excessive alcohol consumption.
• Low intake of potassium, magnesium, and calcium.
• Obesity.

How will I know if I have high blood pressure?

Usually you will not feel any warning signs or symptoms of high blood pressure, and you will not know you have it until a health professional takes a blood pressure reading. Hypertension develops slowly and can cause serious organ damage, usually without any symptoms.

If you develop very severe high blood pressure, you may have headaches, visual disturbances, nausea, and vomiting. Malignant high blood pressure ( hypertensive crisis ), which is hypertension that rises rapidly, can also cause these symptoms. Untreated malignant hypertension can damage the brain, heart, eyes, or kidneys. It is a medical emergency that requires immediate hospitalization.

Over time, if you do not receive treatment for your high blood pressure, you may feel symptoms caused by damage to your heart, kidney, or eyes, including:

• Coronary artery disease , heart attack , heart failure , or abnormal heart beat .
• Kidney (renal failure) .
• Peripheral vascular disease .
• Retinopathy, or damage to the tiny blood vessels that supply blood to the light-sensitive lining of the back of the eye (retina).
• Stroke .

How will a health professional diagnose my high blood pressure?

You will be diagnosed with hypertension if your blood pressure measurements are high (usually above 140/90 mm Hg) on three or more separate occasions. They are usually measured 1 to 2 weeks apart. Except in very severe cases, the diagnosis is not based on a single measurement.

If a health professional suspects you have hypertension, he or she will conduct a physical exam and medical history. If there is reason to suspect that the blood pressure measurements taken in the doctor's office do not represent your accurate blood pressure (if, for example, you have white-coat hypertension ), measuring blood pressure away from the doctor's office may be needed. Your blood pressure can rise more than 20 mm Hg systolic and 10 mm Hg diastolic from white-coat hypertension. Even routine activities, such as attending a meeting, can raise your blood pressure by that amount. Other factors that can raise your blood pressure include commuting to work, exposure to cold, and drinking large amounts of alcohol.

In some cases, you may be asked to check your blood pressure at home 3 times a day and keep a record of the readings. If you are not able to measure your blood pressure accurately at home, you may need to wear an automated blood pressure cuff that periodically inflates and takes blood pressure measurements during the day. This is called ambulatory blood pressure monitoring.

High blood pressure screening tests and programs vary widely in reliability. Results from automated blood pressure testing, such as you might do at a grocery store or pharmacy, may not be accurate. Any high blood pressure measurement discovered during a blood pressure screening program needs to be confirmed by a health professional.

How can I lower my high blood pressure?

If your blood pressure is high (140–159/90–99 mm Hg) and you do not have any organ damage or other risk factors for heart disease, your doctor may recommend lifestyle changes first. These include reducing your salt intake, exercising, managing stress, losing weight if you need to, and following the Dietary Approaches to Stop Hypertension (DASH) diet. The DASH eating plan is a low-sodium, low-fat, and low-saturated-fat diet that emphasizes eating more fruits, vegetables, whole grains, and low-fat dairy foods.

If your blood pressure is 160–179/100–109 mm Hg or higher, your doctor may prescribe medications, such as a diuretic and beta-blocker, along with lifestyle changes. You and your doctor may need to try other medications or another combination of medications to find what works best for you.

Overall, your treatment will depend upon how high your blood pressure is, whether you have other medical conditions, such as diabetes, and whether any organs have already been damaged. Your risk of developing other diseases, especially heart disease, will be another important factor your doctor will consider.

Strategies for treating high blood pressure in pregnant women are quite different. See the topic Preeclampsia and Hypertension During Pregnancy for more information.

Who can treat my high blood pressure?

Although you may have your blood pressure checked outside of a doctor's office, you must see a health professional to confirm that you have high blood pressure, so that you and your doctor can develop a treatment plan that's right for you. A family practice doctor, internist, nurse practitioner, or physician's assistant can diagnose and treat your high blood pressure. If you have extremely high blood pressure or heart problems, you may also need to see a heart specialist (cardiologist).

What lifestyle changes will I have to make to lower my high blood pressure?

If you have primary (essential) hypertension , you will first need to look closely at the foods you eat. Your health professional may recommend that you follow the DASH diet. Losing weight if you need to and exercising will also be important for lowering your blood pressure.

If you smoke cigarettes, you will need to quit. If you are a heavy drinker, you will need to severely cut back on your consumption of alcohol. Also, it may be necessary for you to learn to check your blood pressure at home.

Will I need to take medications for the rest of my life?

High blood pressure treatment, whether it involves medication or lifestyle changes, usually is a lifelong process.

Whether you need medication depends on the severity of your high blood pressure and whether you have other health problems or conditions, such as heart failure or diabetes , or are pregnant.

If your doctor prescribes medication, it is extremely important to take your medications as prescribed.

The high blood pressure stages described in this topic were defined in 1997 by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High blood pressure (JNC VI), a United States group of high blood pressure experts.