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How to Properly Take and Read Your Blood Pressure at Home

Feb 07, 2022

If you're being treated with medication for hypertension, or being followed for borderline high blood pressure, it's imperative to keep track of trends in your blood pressure. Your doctors need to know this information when deciding whether or not to start you on medication to reduce your blood pressure, or if you're already on medication, to see whether it's working or if the dose needs adjustment.

Now, more than ever, patients are tasked with periodically checking their own blood pressure at home. And with telehealth on the rise, you may be asked to take part in self-blood pressure monitoring between virtual or in-person health care visits.

"People spend well over 98% or 99% of their time at home and just a very small period of time when they go to the doctor's office," says Dr. Sharon Reimold, vice chair of internal medicine and a professor of medicine at UT Southwestern Medical Center in Dallas. "When you go to the doctor's office, people are often rushing around, trying to get checked in on time and they're worried about what the physician or provider is going to say – that may be associated with an elevated blood pressure."

Monitoring blood pressure in the familiar environment of home makes sense. "You get a better idea of what home control is, a better idea of how to adjust medication if needed and the patient also has the opportunity to help take care of their own health in a really important way," Reimold says.

Despite pandemic disruptions, it's essential to maintain your health care. "Many people are still afraid to come into the doctor, so we do a lot of telemedicine visits," says Dr. Anjali Mahoney, an associate professor of family medicine with Keck Medicine of USC, the University of Southern California. "We are actually managing a lot of blood pressure from home. It's important that patients know what their blood pressure is and that they know how to take it properly."

Important Home Data

Self-monitoring reflects what's actually happening with your overall blood pressure control, Mahoney notes. "There are a few studies that show that home blood pressure monitoring is more accurate than in-office, just because of white coat hypertension and things like that," she says. Here's how blood pressure readings may vary by setting:

White coat hypertension. This term refers to people who have elevated blood pressure in clinical settings – like their doctor's office – but otherwise have normal blood pressure readings.
Masked hypertension. In contrast, 'masked hypertension' means a patient does not have high pressure measurements in a clinical setting, yet has high out-of-office blood pressure measurements.

By giving a more complete picture of a patient's blood pressure trends, "self-measured BP monitoring has high potential for improving the diagnosis and management of hypertension in the United States," according to a joint policy statement from the American Heart Association and American Medical Association, published in June 2020.

Monitors and Cuffs

The technical term for a traditional blood pressure monitor is a sphygmomanometer. These devices consist of the inflatable cuff that goes around your arm, and the blood pressure gauge to measure the blood flow through the brachial artery – the major artery in your upper arm.

While taking a reading with a sphygmomanometer, clinicians typically place a stethoscope in the bend of your elbow to hear pounding sounds beginning and ending. The beginning sound represents your systolic (top number), and the end of the pounding represents your diastolic (bottom number) in blood pressure readings. Systolic blood pressure measures the force of your heartbeat on the walls of your arteries. Diastolic blood pressure measures the reduced force on the arteries when your heart relaxes.

By contrast, digital monitors automatically provide your blood pressure reading at the touch of a button. No stethoscope is needed, making it possible for you to monitor blood pressure independently. However, digital monitors may be less accurate than those used by health professionals. So, it's important to pick a good at-home blood pressure monitoring device.

Picking a Home Blood Pressure Monitor

Here's some guidance to help you choose the right device

"Blood pressure cuffs that measure on the arm versus the wrist are more accurate," Mahoney says. "A lot of times, wrist cuffs show a higher blood pressure." When monitoring, the cuff goes on the upper arm, near the elbow, she adds.
The cuff needs to fit. "You want to get a blood pressure cuff, first of all, that you can use," Reimold says. So, you should be physically able to put the cuff around your arm, and there should be a good Velcro wrap so it stays there.
Battery-operated monitors that store blood pressure recordings are helpful, Reimold says. "Some new ones allow Bluetooth transferring of data to our electronic medical records," she adds. "That will be something we'll see more of in the future."
The US Blood Pressure Validated Device Listing, developed by the American Medical Association, features devices that have been evaluated for clinical accuracy. You can filter search results to view home monitors only.
Once you've purchased your device, make sure it remains reliable. "I would recommend that (patients) bring their blood pressure monitor at least once a year, so their doctor or clinician can check and make sure that it's accurate, and compare it to the reading at the office," Mahoney says.

Blood Pressure-Taking Tips

With your blood pressure monitor handy, you're ready to go. Follow these tips for the most accurate at-home readings:

"You should be seated," Reimold says. "If you need to go to the bathroom, you should do that before you take your blood pressure."
Sit quietly for five minutes or so. "People need to make sure they haven't (had) any coffee, smoked a cigarette or gone on a run before they check their blood pressure," Mahoney says.
Sit upright in a chair, with your back supported and your feet on the floor. Make sure your arm is supported at heart level, for instance, by resting your arm on a table.
Be relaxed, not rigid. "When you put on the cuff, you're relaxed," Reimold says. "You don’t cross your legs."
Place the cuff on bare skin rather than over a sleeve. "The bottom of the cuff should be right at the bend of the elbow," Mahoney says.
Wait a bit longer if you've taken ibuprofen. "Sometimes those over-the-counter anti-inflammatory medications can raise your blood pressure," Mahoney says, as can decongestants like Sudafed.
When you're really stressed out, your reading could be higher than your norm. "That’s why the five minutes is so important," Mahoney notes.

Timing and Frequency

When self-checking your blood pressure, keep these timing tips in mind:

Get into a routine for each sitting. "You should take three blood pressure checks," Reimold says. "If you're anxious about it, you generally do three in a row, and you can accept the last one or average the second and third one. That just gets rid of some of the concern that a lot of patients have about how high their blood pressure is."

Consider time of day. "Blood pressure is the highest in the morning," Reimold says. "Some people also take their blood pressure medicine in the morning, and if they record their blood pressure before (having) their medicine, then it may be high." Instead, "I ask them generally to pick one or two times – sometime in the evening or maybe later in the morning – and monitor it at those times."

Don't overdo. "One thing I've seen a lot of people do: They have a high reading and they start freaking out," Mahoney says. "They just keep taking it, even in the middle of the night." That's not a good idea, Reimold concurs. "I ask people not to get into the business of taking your blood pressure 20 or 30 times a day," Reimold says. "If you do that, you may be really worried about your blood pressure and that can actually make (it) higher."

Follow your doctor's recommendations on frequency. "Once I have someone whose blood pressure is under excellent control, I think probably just checking their blood pressure once a month or so is useful," Reimold says. "On the other end of that, if I am starting therapy or I'm adjusting therapy, I may ask them to do it one to two times a day, every day." After a week or two, patients provide her with this data to help inform treatment decision-making.

Emergencies and Concerns

Although the main reason for self-monitoring at home is to provide more information to track blood pressure trends, an individual result can sometimes raise a red flag for a possible emergency or at the least be cause for concern. Here's when to contact your doctor:

Medical conditions. "It depends on what's going on," Mahoney says. "If people have comorbidities like diabetes or known hypertension, or if they've had a stroke or a heart attack, then probably (anything) more than 160/80 would raise concern to me."
High blood pressure in new patients. "If they're just newly diagnosed hypertensive, it could go to 180," Mahoney says. "But anything over 180 systolic, which is the top number, raises alarms. And anything over 100 on the bottom number is really concerning."
Accompanying symptoms. For a patient who starts having symptoms suggestive that their blood pressure is too high – which might be headaches, acute breathing problems or other neurological symptoms – Reimold says she'd want that patient to let her know right away regardless of their blood pressure reading.
Abrupt increases. "If somebody who's been well-controlled is all of a sudden reading 160 or 170 (systolic), I want them to let us know so we can decide what we're going to do with therapy," Reimold says. "Generally, we'll advise those people to come into the office. We'll review the medicines, we'll review the diet and make some adjustments. Most of the time we reserve sending patients to the emergency room if they're having symptoms associated with their high blood pressure, or perhaps their blood pressure is over 180."
Low blood pressure. "On the flip side, someone's blood pressure may get too low on their medicine," Reimold says. "If their blood pressure is, say, less than 100, then we would expect them to notify us about that so we could figure out what to do."

Preventative Care

If you're healthy and have never had a problem with high blood pressure, you don't necessarily have to invest in a home monitor. However, adults 18 and older should be medically screened for high blood pressure, at intervals depending on the factors below, according to the U.S. Preventive Services Task Force, an influential health panel of independent medical experts.

Screening with an in-office blood pressure measurement is the initial USPSTF recommendation.
Before starting treatment, the panel advises obtaining blood pressure measurements outside of the clinical setting for diagnostic confirmation. One way is for patients to wear a programmed portable device for 12 to 24 hours while going about their normal, day-to-day activities. Home blood pressure monitoring for a specified period is another alternative.
Screening for hypertension every year for adults ages 40 and older and for all adults at increased risk for hypertension – this includes Black individuals, people with high-normal blood pressure and those with above-normal weight – is a "reasonable option," according to the panel.
Screening less frequently – every three to five years – as appropriate for adults ages 18 to 39 who are not at increased risk for hypertension, and who have a prior normal blood pressure reading, is also deemed reasonable.

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