Can taking your blood pressure too often hurt your arm

The next time you have your blood pressure checked, don’t be surprised if your doctor, nurse, or other health-care provider measures it twice—once in each arm. A significant difference in the pressure recorded in the right and left arms can signal circulatory problems that may lead to stroke, peripheral artery disease, or other cardiovascular problems.

British researchers looked at the results of 20 studies in which blood pressure was measured in both arms. People with an arm-to-arm difference of 15 points or more were twice as likely to have peripheral artery disease—essentially cholesterol-clogged arteries in the arms, legs, or other non-heart parts of the body. The name may sound dismissive, but the disease isn’t. Peripheral artery disease affects at least 12 million Americans, more than heart disease and stroke combined. It kills some, maims others, and makes life painful for countless more.

A blood pressure difference of 10 to 15 points or more between arms also boosted the chances of having a stroke or dying from cardiovascular disease.

Why does blood pressure differ between arms?

Different blood pressure readings in the right and left arms that vary by a few points aren’t anything to worry about. It’s actually quite normal. A difference of more than 10 points, though, could suggest trouble.

In younger people, side-to-side differences in blood pressure can occur when a muscle or something else compresses an artery supplying the arm, or by a structural problem that prevents smooth blood flow through an artery.

In older people, it’s usually due to a blockage arising from atherosclerosis, the artery-clogging disease process at the root of most heart attacks, strokes, peripheral artery disease, and other cardiovascular conditions.

A less common cause of blood pressure that is different in each arm is an aortic dissection. This is a tear inside the wall of the aorta, the main pipeline of oxygenated blood from the heart to the body.

Try this at home

At your next doctor’s visit, ask to have your blood pressure checked in both arms. If there’s a difference greater than 10 point, another test called the ankle-brachial index might be in order to check for peripheral artery disease. It might also be a good time to get serious about taking care of your heart and arteries.

If you take your blood pressure at home, you can do it yourself. There are many good reasons to check your blood pressure at home. The result might be closer to your usual blood pressure than the result in a doctor’s office, and you might do a better job of measuring your blood pressure.

That’s why the Harvard Heart Letter urges people to check their own. All it takes is a home blood pressure monitor, a few simple instructions, and a few minutes (watch our video on taking your blood pressure).

Here are a few tips to help you start monitoring your blood pressure at home:

• Avoid caffeine, alcohol, and nicotine during the 30 minutes before you take your reading.
• Sit quietly for a few minutes with your back supported and your feet on the floor.
• When making the measurement, rest your arm so your elbow is at the level of your heart.
• Wrap the cuff over the bare skin of your upper arm. Measure your blood pressure according to the machine’s instructions. Leave the deflated cuff in place, wait a minute, then take a second reading. If the readings are close, average them. If not, take a third reading and average the three.
• Repeat the procedure in the other arm.

If the different blood pressure readings in your arms are off by more than 10 or 15 points, mention this at your next doctor visit and ask your doctor or nurse to check both arms.

Image: Amorphis/Getty Images

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High blood pressure is one of the top risk factors for heart attack and stroke. It's also common among people who develop severe COVID-19 symptoms.

So, with more people at home practicing social distancing and with fewer chances to check blood pressure at public pharmacy machines or doctor visits, it's more important than ever to know how to do it at home.

How do I select a home blood pressure monitor?

"The readings you get at home are really important, because they reflect the pressure your heart is facing on a day-to-day basis," said Dr. Michael Hochman, a doctor of internal medicine at Keck Medicine of the University of Southern California.

A list of validated home monitors, the first in the United States and commissioned to meet the American Medical Association's criteria, is available at validateBP.org. The Advancement of Medical Instrumentation, the British Hypertension Society and the European Society of Hypertension also certify devices.

The device should measure blood pressure on the upper arm, which produce a more reliable result than those that measure from the wrist.

Many devices are automated. Simply put on the cuff and press a button. The results are displayed digitally.

Some will store readings, calculate an average blood pressure over time, or even transmit them to your doctor.

"When blood pressure monitors cannot transmit readings to a patient's doctor, the next best thing is to have a device that stores the blood pressure readings," said Paul Muntner, professor of epidemiology and associate dean for research at the University of Alabama at Birmingham.

Your health care provider should check the device about once a year to ensure its accuracy.

How do I get the most accurate measurement?

Do not smoke, drink caffeinated beverages or exercise within 30 minutes before measuring your blood pressure. It's important to use a cuff that fits your arm. Cuffs that are too small can artificially raise your blood pressure reading.

With the cuff on your bare arm, sit in an upright position with back supported, feet flat on the floor and your arm supported at heart level. Make sure the bottom of the cuff is directly above the bend of the elbow. Relax for about five minutes before taking a measurement. Resist the urge to talk or look at a cellphone.

Also, make sure your bladder is empty, as a full one can temporarily raise blood pressure.

Some medications, including over-the-counter pain relievers called NSAIDs and common decongestants, can elevate blood pressure. Alcohol, caffeine, smoking, salt intake and stress can, too.

Muntner recommended people check their blood pressure at the same time each day, such as twice in the morning and twice in the evening for one week, then talk with their doctor about the results.

"Blood pressure fluctuates a lot, so a patient shouldn't worry about one high reading," Muntner said. "If the average over a full week is high, there's reason for people to talk to their doctors. If not, people should continue practicing heart-healthy behaviors and check their BP in the future."

What is the ideal blood pressure?

The device will give you a systolic number (upper) – the pressure against your artery walls when your heart beats – and a diastolic number (lower) – the pressure between beats.

For normal readings of less than 120/80, Muntner said it's not necessary to check blood pressure again for at least six months.

If the top number is 130 or greater, or the bottom number is 80 or greater, Muntner recommended talking with your doctor about your overall risk for heart attack and stroke.

"If someone is at higher risk – for example, they smoke or have diabetes – then they should be started on blood pressure-lowering medication," he said.

"If it's very high, 180 or higher (over) 110 or higher, you should call your doctor right away. The longer your blood pressure is high, the more you are at risk for heart attack and stroke."

There are many ways to lower blood pressure, including medication, getting more exercise, eating plenty of fruits and vegetables, not smoking, reducing salt and alcohol consumption, lowering stress and losing weight.

"For some people, it may be easier to reduce the amount of salt they eat. For others, it may be easier to do a little physical activity," Muntner said. "The important thing is to do the things that work for each individual."

If you have questions or comments about this story, please email [email protected].

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