High blood pressure (hypertension) is a common condition in which the long-term force of the blood against your artery walls is high enough that it may eventually cause health problems, such as heart disease.

Blood pressure is determined both by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure. A blood pressure reading is given in millimeters of mercury (mm Hg). It has two numbers.

• Top number (systolic pressure). The first, or upper, number measures the pressure in your arteries when your heart beats.
• Bottom number (diastolic pressure). The second, or lower, number measures the pressure in your arteries between beats.

You can have high blood pressure for years without any symptoms. Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke. Fortunately, high blood pressure can be easily detected. And once you know you have high blood pressure, you can work with your doctor to control it.

Most people with high blood pressure have no signs or symptoms, even if blood pressure readings reach dangerously high levels.

A few people with high blood pressure may have headaches, shortness of breath or nosebleeds, but these signs and symptoms aren't specific and usually don't occur until high blood pressure has reached a severe or life-threatening stage.

When to see a doctor

You'll likely have your blood pressure taken as part of a routine doctor's appointment.

Ask your doctor for a blood pressure reading at least every two years starting at age 18. If you're age 40 or older, or you're 18 to 39 with a high risk of high blood pressure, ask your doctor for a blood pressure reading every year.

Blood pressure generally should be checked in both arms to determine if there's a difference. It's important to use an appropriate-sized arm cuff.

Your doctor will likely recommend more-frequent readings if you've already been diagnosed with high blood pressure or have other risk factors for cardiovascular disease. Children age 3 and older will usually have blood pressure measured as a part of their yearly checkups.

If you don't regularly see your doctor, you may be able to get a free blood pressure screening at a health resource fair or other locations in your community. You can also find machines in some stores that will measure your blood pressure for free.

Public blood pressure machines, such as those found in pharmacies, may provide helpful information about your blood pressure, but they may have some limitations. The accuracy of these machines depends on several factors, such as a correct cuff size and proper use of the machines. Ask your doctor for advice on using public blood pressure machines.

There are two types of high blood pressure.

Primary (essential) hypertension

For most adults, there's no identifiable cause of high blood pressure. This type of high blood pressure, called primary (essential) hypertension, tends to develop gradually over many years.

Secondary hypertension

Some people have high blood pressure caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions and medications can lead to secondary hypertension, including:

• Obstructive sleep apnea
• Kidney disease
• Adrenal gland tumors
• Thyroid problems
• Certain defects you're born with (congenital) in blood vessels
• Certain medications, such as birth control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs
• Illegal drugs, such as cocaine and amphetamines

High blood pressure has many risk factors, including:

• Age. The risk of high blood pressure increases as you age. Until about age 64, high blood pressure is more common in men. Women are more likely to develop high blood pressure after age 65.
• Race. High blood pressure is particularly common among people of African heritage, often developing at an earlier age than it does in whites. Serious complications, such as stroke, heart attack and kidney failure, also are more common in people of African heritage.
• Family history. High blood pressure tends to run in families.
• Being overweight or obese. The more you weigh, the more blood you need to supply oxygen and nutrients to your tissues. As the amount of blood flow through your blood vessels increases, so does the pressure on your artery walls.
• Not being physically active. People who are inactive tend to have higher heart rates. The higher your heart rate, the harder your heart must work with each contraction and the stronger the force on your arteries. Lack of physical activity also increases the risk of being overweight.
• Using tobacco. Not only does smoking or chewing tobacco immediately raise your blood pressure temporarily, but the chemicals in tobacco can damage the lining of your artery walls. This can cause your arteries to narrow and increase your risk of heart disease. Secondhand smoke also can increase your heart disease risk.
• Too much salt (sodium) in your diet. Too much sodium in your diet can cause your body to retain fluid, which increases blood pressure.
• Too little potassium in your diet. Potassium helps balance the amount of sodium in your cells. A proper balance of potassium is critical for good heart health. If you don't get enough potassium in your diet, or you lose too much potassium due to dehydration or other health conditions, sodium can build up in your blood.

• Drinking too much alcohol. Over time, heavy drinking can damage your heart. Having more than one drink a day for women and more than two drinks a day for men may affect your blood pressure.

  If you drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and two drinks a day for men. One drink equals 12 ounces of beer, 5 ounces of wine or 1.5 ounces of 80-proof liquor.

• Stress. High levels of stress can lead to a temporary increase in blood pressure. Stress-related habits such as eating more, using tobacco or drinking alcohol can lead to further increases in blood pressure.
• Certain chronic conditions. Certain chronic conditions also may increase your risk of high blood pressure, including kidney disease, diabetes and sleep apnea.

Sometimes pregnancy contributes to high blood pressure as well.

Although high blood pressure is most common in adults, children may be at risk, too. For some children, high blood pressure is caused by problems with the kidneys or heart. But for a growing number of kids, poor lifestyle habits — such as an unhealthy diet and lack of exercise — contribute to high blood pressure.

The excessive pressure on your artery walls caused by high blood pressure can damage your blood vessels as well as your organs. The higher your blood pressure and the longer it goes uncontrolled, the greater the damage.

Uncontrolled high blood pressure can lead to complications including:

• Heart attack or stroke. High blood pressure can cause hardening and thickening of the arteries (atherosclerosis), which can lead to a heart attack, stroke or other complications.
• Aneurysm. Increased blood pressure can cause your blood vessels to weaken and bulge, forming an aneurysm. If an aneurysm ruptures, it can be life-threatening.
• Heart failure. To pump blood against the higher pressure in your vessels, the heart has to work harder. This causes the walls of the heart's pumping chamber to thicken (left ventricular hypertrophy). Eventually, the thickened muscle may have a hard time pumping enough blood to meet your body's needs, which can lead to heart failure.
• Weakened and narrowed blood vessels in your kidneys. This can prevent these organs from functioning normally.
• Thickened, narrowed or torn blood vessels in the eyes. This can result in vision loss.
• Metabolic syndrome. This syndrome is a group of disorders of your body's metabolism, including increased waist size, high triglycerides, decreased high-density lipoprotein (HDL) cholesterol (the "good" cholesterol), high blood pressure and high insulin levels. These conditions make you more likely to develop diabetes, heart disease and stroke.
• Trouble with memory or understanding. Uncontrolled high blood pressure may also affect your ability to think, remember and learn. Trouble with memory or understanding concepts is more common in people with high blood pressure.
• Dementia. Narrowed or blocked arteries can limit blood flow to the brain, leading to a certain type of dementia (vascular dementia). A stroke that interrupts blood flow to the brain also can cause vascular dementia.

Your doctor will ask questions about your medical history and do a physical examination. The doctor, nurse or other medical assistant will place an inflatable arm cuff around your arm and measure your blood pressure using a pressure-measuring gauge.

Your blood pressure generally should be measured in both arms to determine if there is a difference. It's important to use an appropriate-sized arm cuff.

Blood pressure measurements fall into several categories:

• Normal blood pressure. Your blood pressure is normal if it's below 120/80 mm Hg.
• Elevated blood pressure. Elevated blood pressure is a systolic pressure ranging from 120 to 129 mm Hg and a diastolic pressure below (not above) 80 mm Hg. Elevated blood pressure tends to get worse over time unless steps are taken to control blood pressure. Elevated blood pressure may also be called prehypertension.
• Stage 1 hypertension. Stage 1 hypertension is a systolic pressure ranging from 130 to 139 mm Hg or a diastolic pressure ranging from 80 to 89 mm Hg.
• Stage 2 hypertension. More-severe hypertension, stage 2 hypertension is a systolic pressure of 140 mm Hg or higher or a diastolic pressure of 90 mm Hg or higher.
• Hypertensive crisis. A blood pressure measurement higher than 180/120 mm Hg is an emergency situation that requires urgent medical care. If you get this result when you take your blood pressure at home, wait five minutes and retest. If your blood pressure is still this high, contact your doctor immediately. If you also have chest pain, vision problems, numbness or weakness, breathing difficulty, or any other signs and symptoms of a stroke or heart attack, call 911 or your local emergency medical number.

Both numbers in a blood pressure reading are important. But after age 50, the systolic reading is even more important. Isolated systolic hypertension is a condition in which the diastolic pressure is normal (less than 80 mm Hg) but systolic pressure is high (greater than or equal to 130 mm Hg). This is a common type of high blood pressure among people older than 65.

Because blood pressure normally varies during the day and may increase during a doctor visit (white coat hypertension), your doctor will likely take several blood pressure readings at three or more separate appointments before diagnosing you with high blood pressure.

Taking your blood pressure at home

Your doctor may ask you to record your blood pressure at home to provide additional information and confirm if you have high blood pressure.

Home monitoring is an important way to confirm if you have high blood pressure, to check if your blood pressure treatment is working or to diagnose worsening high blood pressure.

Home blood pressure monitors are widely available and inexpensive, and you don't need a prescription to buy one. Home blood pressure monitoring isn't a substitute for visits to your doctor, and home blood pressure monitors may have some limitations.

Make sure to use a validated device, and check that the cuff fits. Bring the monitor with you to your doctor's office to check its accuracy once a year. Talk to your doctor about how to start checking your blood pressure at home.

Devices that measure your blood pressure at your wrist or finger aren't recommended by the American Heart Association because they can provide less reliable results.

Tests

If you have high blood pressure, your doctor may recommend tests to confirm the diagnosis and check for underlying conditions that can cause hypertension.

• Ambulatory monitoring. This 24-hour blood pressure monitoring test is used to confirm if you have high blood pressure. The device used for this test measures your blood pressure at regular intervals over a 24-hour period and provides a more accurate picture of blood pressure changes over an average day and night. However, these devices aren't available in all medical centers, and they may not be reimbursed.
• Lab tests. Your doctor may recommend a urine test (urinalysis) and blood tests, including a cholesterol test.
• Electrocardiogram (ECG or EKG). This quick and painless test measures your heart's electrical activity.
• Echocardiogram. Depending on your signs and symptoms and test results, your doctor may order an echocardiogram to check for more signs of heart disease. An echocardiogram uses sound waves to produce images of the heart.

Changing your lifestyle can help control and manage high blood pressure. Your doctor may recommend that you make lifestyle changes including:

• Eating a heart-healthy diet with less salt
• Getting regular physical activity
• Maintaining a healthy weight or losing weight if you're overweight or obese
• Limiting the amount of alcohol you drink

But sometimes lifestyle changes aren't enough. If diet and exercise don't help, your doctor may recommend medication to lower your blood pressure.

Medications

The type of medication your doctor prescribes for high blood pressure depends on your blood pressure measurements and overall health. Two or more blood pressure drugs often work better than one. Sometimes finding the most effective medication or combination of drugs is a matter of trial and error.

You should aim for a blood pressure treatment goal of less than 130/80 mm Hg if:

• You're a healthy adult age 65 or older
• You're a healthy adult younger than age 65 with a 10% or higher risk of developing cardiovascular disease in the next 10 years
• You have chronic kidney disease, diabetes or coronary artery disease

Ask your doctor what your blood pressure treatment goal should be. Also, the ideal blood pressure treatment goal can vary with age and health conditions, particularly if you're older than age 65.

Medications used to treat high blood pressure include:

• Diuretics. Diuretics, sometimes called water pills, are medications that help your kidneys eliminate sodium and water from the body. These drugs are often the first medications tried to treat high blood pressure.

  There are different classes of diuretics, including thiazide, loop and potassium sparing. Which one your doctor recommends depends on your blood pressure measurements and other health conditions, such a kidney disease or heart failure. Diuretics commonly used to treat blood pressure include chlorthalidone, hydrochlorothiazide (Microzide) and others.

  A common side effect of diuretics is increased urination, which could reduce potassium levels. If you have a low potassium level, your doctor may add a potassium-sparing diuretic — such as triamterene (Dyazide, Maxide) or spironolactone (Aldactone) — to your treatment.

• Angiotensin-converting enzyme (ACE) inhibitors. These medications — such as lisinopril (Prinivil, Zestril), benazepril (Lotensin), captopril and others — help relax blood vessels by blocking the formation of a natural chemical that narrows blood vessels.
• Angiotensin II receptor blockers (ARBs). These medications relax blood vessels by blocking the action, not the formation, of a natural chemical that narrows blood vessels. ARBs include candesartan (Atacand), losartan (Cozaar) and others.

• Calcium channel blockers. These medications — including amlodipine (Norvasc), diltiazem (Cardizem, Tiazac, others) and others — help relax the muscles of your blood vessels. Some slow your heart rate. Calcium channel blockers may work better for older people and people of African heritage than do ACE inhibitors alone.

  Don't eat or drink grapefruit products when taking calcium channel blockers. Grapefruit increases blood levels of certain calcium channel blockers, which can be dangerous. Talk to your doctor or pharmacist if you're concerned about interactions.

Additional medications sometimes used to treat high blood pressure

If you're having trouble reaching your blood pressure goal with combinations of the above medications, your doctor may prescribe:

• Alpha blockers. These medications reduce nerve signals to blood vessels, lowering the effects of natural chemicals that narrow blood vessels. Alpha blockers include doxazosin (Cardura), prazosin (Minipress) and others.
• Alpha-beta blockers. Alpha-beta blockers block nerve signals to blood vessels and slow the heartbeat to reduce the amount of blood that must be pumped through the vessels. Alpha-beta blockers include carvedilol (Coreg) and labetalol (Trandate).

• Beta blockers. These medications reduce the workload on your heart and widen your blood vessels, causing your heart to beat slower and with less force. Beta blockers include acebutolol, atenolol (Tenormin) and others.

  Beta blockers aren't usually recommended as the only medication you're prescribed, but they may be effective when combined with other blood pressure medications.

• Aldosterone antagonists. These drugs also are considered diuretics. Examples are spironolactone and eplerenone (Inspra). These drugs block the effect of a natural chemical that can lead to salt and fluid buildup, which can contribute to high blood pressure. They may be used to treat resistant hypertension.

• Renin inhibitors. Aliskiren (Tekturna) slows the production of renin, an enzyme produced by your kidneys that starts a chain of chemical steps that increases blood pressure.

  Due to a risk of serious complications, including stroke, you shouldn't take aliskiren with ACE inhibitors or ARBs.

• Vasodilators. These medications include hydralazine and minoxidil. They work directly on the muscles in the walls of your arteries, preventing the muscles from tightening and your arteries from narrowing.
• Central-acting agents. These medications prevent your brain from telling your nervous system to increase your heart rate and narrow your blood vessels. Examples include clonidine (Catapres, Kapvay), guanfacine (Intuniv) and methyldopa.

Treating resistant hypertension

If your blood pressure remains stubbornly high despite taking at least three different types of high blood pressure drugs, one of which usually should be a diuretic, you may have resistant hypertension.

You're also considered to have resistant hypertension if you have controlled high blood pressure but are taking four different types of medications at the same time to achieve that control. If you do, your doctor should investigate the possibility of a secondary cause of the high blood pressure.

Having resistant hypertension doesn't mean your blood pressure will never get lower. If you and your doctor can determine the cause, a more effective treatment plan can be created to help you meet your goal blood pressure.

Treating resistant hypertension may involve many steps, including:

• Changing your high blood pressure medications to determine which combinations and doses work best
• Reviewing all the medications you take, including those that you take for other conditions or buy without a prescription
• Monitoring your blood pressure at home to see if going to the doctor causes your blood pressure to increase (white coat hypertension)
• Making healthy lifestyle changes, such as eating a healthy diet with less salt, maintaining a healthy weight and limiting alcohol

You should always take blood pressure medications as prescribed. Never skip a dose or abruptly stop taking your blood pressure medication. Suddenly stopping certain blood pressure drugs, such as beta blockers, can cause a sharp increase in blood pressure (rebound hypertension).

If you skip doses because you can't afford the medications, because you have side effects or because you simply forget to take your medications, talk to your doctor about solutions. Don't change your treatment without your doctor's guidance.

Potential future treatments

Researchers continue to study catheter-based ultrasound and radiofrequency ablation of the kidney's sympathetic nerves (renal denervation) as a treatment for resistant hypertension. Early studies showed some benefit, but more-robust studies found that the therapy does not significantly lower blood pressure in people with resistant hypertension. More research is underway to determine what role, if any, this therapy may have in treating hypertension.

Lifestyle changes can help you control and prevent high blood pressure, even if you're taking blood pressure medication. Here's what you can do:

• Eat healthy foods. Eat a heart-healthy diet. Try the Dietary Approaches to Stop Hypertension (DASH) diet, which emphasizes fruits, vegetables, whole grains, poultry, fish and low-fat dairy foods. Get plenty of potassium, which can help prevent and control high blood pressure. Eat less saturated fat and trans fat.

• Decrease the salt in your diet. Aim to limit sodium to less than 2,300 milligrams (mg) a day or less. However, a lower sodium intake — 1,500 mg a day or less — is ideal for most adults.

  While you can reduce the amount of salt you eat by putting down the saltshaker, you generally should also pay attention to the amount of salt that's in the processed foods you eat, such as canned soups or frozen dinners.

• Maintain a healthy weight. Keeping a healthy weight, or losing weight if you're overweight or obese, can help you control your high blood pressure and lower your risk of related health problems. In general, you may reduce your blood pressure by about 1 mm Hg with each kilogram (about 2.2 pounds) of weight you lose.

• Increase physical activity. Regular physical activity can help lower your blood pressure, manage stress, keep your weight under control and reduce your risk of many health conditions. If you have high blood pressure, consistent moderate- to high-intensity workouts can lower your top blood pressure reading by about 11 mm Hg and the bottom number by about 5 mm Hg.

  Aim for at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity, or a combination of moderate and vigorous activity. For example, try brisk walking for about 30 minutes most days of the week. Or try interval training, in which you alternate short bursts of intense activity with short recovery periods of lighter activity. Aim to do muscle-strengthening exercises at least two days a week.

• Limit alcohol. Even if you're healthy, alcohol can raise your blood pressure. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women, and up to two drinks a day for men. One drink equals 12 ounces of beer, 5 ounces of wine or 1.5 ounces of 80-proof liquor.
• Don't smoke. Tobacco can injure blood vessel walls and speed up the process of buildup of plaque in the arteries. If you smoke, ask your doctor to help you quit.
• Manage stress. Reduce stress as much as possible. Practice healthy coping techniques, such as muscle relaxation, deep breathing or mindfulness. Getting regular physical activity and plenty of sleep can help, too.

• Monitor your blood pressure at home. Home blood pressure monitoring allows you to keep a daily log of blood pressure measurements. Your doctor can review the information to determine if your medication is working or if you're having complications. Home blood pressure monitoring isn't a substitute for visits to your doctor. Even if you get normal readings, don't stop or change your medications or alter your diet without talking to your doctor first.

  If your blood pressure is under control, ask your doctor about how often you need to check it.

• Practice relaxation or slow, deep breathing. Practice taking deep, slow breaths to help relax. Some research shows that slow, paced breathing (five to seven deep breaths per minute) combined with mindfulness techniques can reduce blood pressure. There also are some devices available that promote slow, deep breathing. According to the American Heart Association, device-guided breathing may be a reasonable nondrug option for lowering blood pressure, especially if you have anxiety with high blood pressure or can't tolerate standard treatments well.
• Control blood pressure during pregnancy. Women with high blood pressure should discuss with their doctors how to control their blood pressure during pregnancy.

Although diet and exercise are the most appropriate tactics to lower your blood pressure, some supplements also may help lower it. However, more research is needed to determine the potential benefits. These supplements include:

• Fiber, such as blond psyllium and wheat bran
• Minerals, such as magnesium, calcium and potassium
• Folic acid
• Supplements or products that increase nitric oxide or widen blood vessels (vasodilators), such as cocoa, coenzyme Q10, L-arginine and garlic
• Omega-3 fatty acids, found in fatty fish, high-dose fish oil supplements and flaxseed

Researchers are also studying whether vitamin D can reduce blood pressure, but evidence is conflicting. More research is needed.

While it's best to include these supplements in your diet as foods, you can also take supplement pills or capsules. Talk to your doctor before adding any of these supplements to your blood pressure treatment. Some supplements can interact with medications, causing harmful side effects, such as an increased bleeding risk that could be life-threatening.

You can also practice relaxation techniques, such as deep breathing or mindfulness, to help you relax and reduce your stress level. These practices may temporarily reduce your blood pressure.

High blood pressure isn't a problem that you can treat and then ignore. It's a condition you need to manage for the rest of your life. To keep your blood pressure under control:

• Take your medications properly. If side effects or costs pose problems, don't stop taking your medications. Ask your doctor about other options.
• Schedule regular doctor visits. It takes a team effort to treat high blood pressure successfully. Your doctor can't do it alone, and neither can you. Work with your doctor to bring your blood pressure to a safe level and keep it there.
• Adopt healthy habits. Eat healthy foods, lose excess weight and get regular physical activity. Limit alcohol. If you smoke, quit.
• Manage stress. Say no to extra tasks, release negative thoughts, maintain good relationships, and remain patient and optimistic.

Sticking to lifestyle changes can be difficult, especially if you don't see or feel any symptoms of high blood pressure. If you need motivation, remember the risks associated with uncontrolled high blood pressure. It may help to enlist the support of your family and friends as well.

If you think you may have high blood pressure, make an appointment with your doctor to have your blood pressure checked.

No special preparations are necessary to have your blood pressure checked. You might want to wear a short-sleeved shirt to your appointment so that the blood pressure cuff can fit around your arm properly. Avoid eating, drinking caffeinated beverages and smoking right before your test. Plan to use the toilet before having your blood pressure measured.

Because some medications, such as over-the-counter cold medicines, pain medications, antidepressants, birth control pills and others, can raise your blood pressure, it might be a good idea to bring a list of medications and supplements you take to your doctor's appointment. Don't stop taking any prescription medications that you think may affect your blood pressure without your doctor's advice.

Because appointments can be brief, and because there's often a lot to discuss, it's a good idea to be prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Write down any symptoms that you're having. High blood pressure rarely has symptoms, but it's a risk factor for heart disease. Letting your doctor know if you have symptoms such as chest pains or shortness of breath can help your doctor decide how aggressively to treat your high blood pressure.
• Write down key personal information, including a family history of high blood pressure, high cholesterol, heart disease, stroke, kidney disease or diabetes, and any major stresses or recent life changes.
• Make a list of all medications, vitamins or supplements that you're taking.
• Take a family member or friend along, if possible. Sometimes it can be difficult to remember all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Be prepared to discuss your diet and exercise habits. If you don't already follow a diet or exercise routine, be ready to talk to your doctor about any challenges you might face in getting started.
• Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For high blood pressure, some basic questions to ask your doctor include:

• What kinds of tests will I need?
• Do I need any medications?
• What foods should I eat or avoid?
• What's an appropriate level of physical activity?
• How often do I need to schedule appointments to check my blood pressure?
• Should I monitor my blood pressure at home?
• What are the alternatives to the primary approach that you're suggesting?
• I have other health conditions. How can I best manage them together?
• Are there any restrictions that I need to follow?
• Should I see a specialist?
• Is there a generic alternative to the medicine you're prescribing for me?
• Are there any brochures or other printed material that I can take home with me?
• What websites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What you can do in the meantime

It's never too early to make healthy lifestyle changes, such as quitting smoking, eating healthy foods and getting more exercise. These are main ways to protect yourself against high blood pressure and its complications, including heart attack and stroke.