Blood pressure is a measure of how hard the blood pushes against the walls of your arteries as it moves through your body. It's normal for blood pressure to go up and down throughout the day, but if it stays up, you have high blood pressure.

For your doctor to confirm that you have high blood pressure, your blood pressure must be at least 140/90 on three or more separate occasions. It is usually measured 1 to 2 weeks apart.

Measuring blood pressure

1. A blood pressure cuff is inflated around your upper arm. This stops the blood from flowing through the artery in your arm.
2. The cuff is slowly deflated. A stethoscope placed on the inside of your elbow picks up the sound of the blood beginning to flow through the artery again.
3. As the cuff deflates even more, the sound eventually stops.

Blood pressure is recorded as two measurements:

• Systolic pressure: This is the reading on the gauge when blood flow is first heard. It's the highest pressure that occurs when your heart muscles contract.
• Diastolic pressure: This is the reading on the gauge when blood flow can no longer be heard. It's the lowest pressure that occurs when your heart relaxes between beats.

Blood pressures are measured in millimeters of mercury (mm Hg). Systolic pressure, the higher of the two readings, is measured first. Diastolic pressure is the lower reading. For example, if your systolic pressure is 120 mm Hg and your diastolic pressure is 80 mm Hg, your blood pressure is recorded as 120/80, or "120 over 80."

When you take your own blood pressure, you can do it at different times and in different places, such as at home, at work, and when you travel. This helps your doctor to:

• Decide whether you have high blood pressure.
• Check whether a certain medicine is helping to lower your blood pressure.
• See if you have low blood pressure that may be caused by irregular heart rhythms, certain medicines, or other medical conditions.
• Make sure that any medicines you take for other problems are not causing episodes of high blood pressure.

When you have high blood pressure, taking your own measurements can help you see how medicine or lifestyle changes are helping to lower your blood pressure. It can help you feel more involved in and more in control of your own health care.

Some people have a big rise in blood pressure only when they are in a doctor's office. This is called "white-coat hypertension." It probably is caused by worry about the doctor visit. By checking blood pressure at home, these people can often find out whether their blood pressure readings generally are lower when they are not in the doctor's office.

Blood pressure devices

There are two types of blood pressure devices:

• Manual devices. This is the kind of device you usually see at the doctor's office. It involves using a stethoscope to listen to the heartbeat.
• Electronic (digital) devices. These are easier to use. They do the listening for you.

When you first get a blood pressure device, check its accuracy. Do this by comparing its readings with those you get at the doctor's office. Ask your doctor or nurse to watch you use your device to make sure that you are doing it right and that it works right. It's a good idea to have your device checked every year at the doctor's office.

The size of the Reference blood pressure cuff Opens New Window Reference Opens New Window and where you place it can greatly affect how accurate your device is. If the cuff is Reference too small Opens New Window Reference Opens New Window or Reference too large Opens New Window Reference Opens New Window, the results won't be right. You may have to measure your arm and choose a monitor that comes in the right size.

Measure blood pressure in your arm. Blood pressure monitors used on the wrist aren't as reliable as those that use arm cuffs. Wrist monitors should be used only by people who can't use arm cuffs for physical reasons. And devices that use finger monitors aren't recommended at all.^{Reference 2}

Getting ready

Before you take your blood pressure:

• Don't eat, smoke, or exercise for at least 30 minutes before you take your blood pressure. And don't use any medicines that can raise blood pressure, such as certain nasal sprays.
• Rest at least 5 minutes before you take a reading. Sit in a comfortable, relaxed position with both feet on the floor. Don't move or talk while you are measuring your blood pressure.
• Try not to take your blood pressure if you are nervous or upset.
• If you can, use the same arm for every reading. Readings may be 10 to 20 mm Hg different between your right arm and your left arm.

Remember that blood pressure readings vary throughout the day. They usually are highest in the morning after you wake up and move around. They decrease throughout the day and are lowest in the evening.

Using an electronic (digital) blood pressure monitor

1. Sit with your arm slightly bent and resting comfortably on a table so that your upper arm is on the same level as your heart.
2. Wrap the blood pressure cuff around your bare upper arm. The lower edge of the cuff should be about 1 inch (2.5 cm) Reference above the bend of your elbow Opens New Window Reference Opens New Window.
3. Press the on/off button.
4. Wait until the ready-to-measure "heart" symbol appears next to zero in the display window.
5. Press the start button. The cuff will inflate.
6. After a few seconds, the cuff will begin to deflate. The numbers on the screen will begin to drop.
7. When the measurement is complete, the heart symbol stops flashing. The numbers tell you your blood pressure and pulse.

Using a manual blood pressure monitor

1. Sit with your arm slightly bent and resting comfortably on a table so that your upper arm is on the same level as your heart.
2. Wrap the blood pressure cuff around your bare upper arm. The lower edge of the cuff should be about 1 inch (2.5 cm) Reference above the bend of your elbow Opens New Window Reference Opens New Window.
3. Close the valve on the rubber inflating bulb. Squeeze the bulb rapidly with your opposite hand to inflate the cuff. Keep squeezing until the dial or column of mercury reads about 30 mm Hg higher than your usual Reference systolic pressure Opens New Window. (If you don't know your usual pressure, inflate the cuff to 210 mm Hg.) The pressure in the cuff will temporarily stop all blood flow in your arm.
4. Put the stethoscope over the large artery slightly above the inside of your elbow. You can find this artery by feeling for its pulse with the fingers of your other hand. If you are using a cuff with a built-in stethoscope, be sure the part of the cuff with the stethoscope is over the artery.
5. Open the valve on the bulb just slightly. The numbers on the pressure dial or mercury tube should fall gradually—about 2 to 3 mm Hg per second. Some devices automatically control the fall at this rate.
6. Listen through the stethoscope. As you watch the pressure slowly fall, note the number on the dial or tube when you first start to hear a pulsing or tapping sound. The sound is caused by the blood starting to move through the closed artery. This is your systolic blood pressure.
7. Continue letting the air out slowly. The sounds will become muffled and finally will disappear. Note the number when the sounds completely disappear. This is your diastolic blood pressure. Finally, let out all the remaining air to take the cuff off.

Keep a blood pressure diary

Everyone's blood pressure changes from day to day and even from minute to minute sometimes. So taking your own blood pressure works best when you also keep a diary.

Your doctor may give you a form to use, or you can use a home blood pressure log (What is a Reference PDF Opens New Window document?).

Write down your Reference systolic Opens New Window and Reference diastolic Opens New Window pressures, the date, and time.

Also write down any medicine you take and what time you take it. Record anything that causes you stress. These records can help your doctor make sure you get the right treatment.

Blood pressure tips

• Don't let the stethoscope rub on the cuff or your clothing. This may cause noises that make your pulse hard to hear.
• If you're not familiar with using a stethoscope, you may want to get help from someone who is. The accuracy of a blood pressure recording depends on putting the stethoscope in just the right place.
• In the beginning, always take your blood pressure 3 times. Wait 1 to 2 minutes between recordings to let the blood flow back into your arm. After you get better at doing it, you probably will need to do it only once or twice each time.
• Check your blood pressure cuff often. Make sure the rubber tubing, bulb, valves, and cuff are in good condition. Even a small hole or crack in the tubing can lead to inaccurate results.
• Take your monitor to your doctor's office once a year to have it checked.
• You may not be able to use a manual blood pressure monitor if you have poor hearing or eyesight or if you can't move your hands and fingers easily. For people with these limitations, an electronic arm- or wrist-cuff model is better.
• You may not be able to use an arm-cuff monitor if your arms are very large. If that is the case, have your doctor check your blood pressure regularly. An accurate blood pressure measurement is very important when you are very overweight, so don't rely on a wrist-cuff model.

Talk with your doctor

If you have questions about this information, print it out and take it with you when you visit your doctor. You may want to use a highlighter to mark areas or make notes in the margins of the pages where you have questions.

If you would like more information on taking your blood pressure, see the topic Reference Home Blood Pressure Test.

If you would like more information on high blood pressure, the following resources are available:

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