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FITNESS HEALTH NATURAL-BEAUTY

Monitoring blood pressure at home? Make sure you follow these steps

Illustration of dark-haired woman seated at table, arm extended, using a blood pressure monitor; notebook and a bowl of green apples near her

When was the last time you had your blood pressure checked? All adults should have this simple test at least once a year.

If a blood pressure reading at your doctor’s office is elevated — that is, higher than a healthy range — current guidelines from the US Preventive Services Task Force recommend repeating the measurement outside of a clinic setting before starting treatment. But that’s not the only reason why your doctor may suggest regularly tracking your blood pressure at home.

Why monitor blood pressure at home?

“Some people have blood pressure elevations only at the doctor’s office, which is known as white-coat hypertension,” says Dr. Stephen Juraschek, associate professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center. One of the best ways to know if your blood pressure is truly higher than normal is to measure it multiple times at home.

Home monitoring is also a good idea:

  • if your doctor asks you to track readings to help decide if you need to start taking medication to lower blood pressure
  • if you’ve been diagnosed with high blood pressure and need to adjust your medications to make sure you’re reaching your blood pressure target
  • if you’re pregnant or had a baby in recent months and your health team is concerned about preeclampsia. This condition is a severe form of high blood pressure that can harm vital organs like the kidneys. When not promptly treated, it sometimes leads to seizures, stroke, or even death.

Which home blood pressure monitor should I buy?

  • Look for a monitor that’s been validated, which means the device has been independently reviewed for accuracy.
  • Avoid monitors that feature cuffs used on the wrist or fingertip. These aren’t as accurate as upper-arm cuffs.
  • Choose and use the right size cuff. Measure the circumference of your upper arm midway between your elbow and shoulder. Most home monitor cuffs can accommodate arm circumferences of 9 to 17 inches, but smaller and larger cuffs are available. A too-small cuff can lead to an artificially high reading, while a loose cuff can give a falsely low reading. For example, a 2023 randomized study of automated blood pressure monitors tested a regular size cuff on adults who need a different size cuff. The researchers found systolic blood pressure readings increased 19.5 mm Hg for participants who should have used an extra-large cuff, and by 4.8 mm Hg for participants who should have used a large cuff.

Very basic models cost as little as $25. But more expensive models, which range from about $50 to $100, may be more convenient to use. They can store multiple readings and send the data to your computer or smartphone — or even directly to the patient portal at your doctor’s office.

Three key points about blood pressure readings

Home blood pressure monitoring is a bit more involved than some people assume. “It’s not something you just do sporadically or whenever you have time,” says Dr. Juraschek.

  • Blood pressure fluctuates throughout the day, which means one isolated reading doesn’t provide accurate information.
  • If you check your blood pressure when you’re upset or stressed, it’s likely to be high. If you take it again right away, you may get another high reading, which feeds a cycle of anxiety and elevated readings, he says.
  • Consistent, repeated measurements provide a far more useful assessment than occasional measurements.

How often should you take your blood pressure at home?

Ask your doctor how often and what time of day to take your blood pressure.

“The gold standard for home monitoring is to take 28 separate measurements, which you can then average to get a representative reading,” says Dr. Juraschek.

That means taking your blood pressure four times a day — twice in the morning and twice in the evening — for seven days in a row. However, even 12 measurements over three days is reasonable, especially if you include one weekend day, Dr. Juraschek says. Your doctor can advise you about what makes the most sense for your situation.

How can you get an accurate blood pressure reading?

Common mistakes can raise your blood pressure reading by a few points, or as much as 10 or even up to 25 points in some cases. Here’s what to do or avoid — and why — for an accurate blood pressure reading.

Wait at least 30 minutes after smoking, consuming caffeine or alcohol, or exercising before taking blood pressure.

Why? Caffeine and nicotine constrict blood vessels and boost your heart rate, which can raise blood pressure. Alcohol dilates blood vessels, possibly lowering blood pressure. And exercise increases heart rate and blood pressure.

Empty your bladder.

Why? A full bladder can put pressure on and reduce blood flow to your kidneys. Your body’s natural response is to raise your blood pressure to make sure your kidneys are getting enough blood.

Sit comfortably, supporting your arm near heart height.

Sit back in your chair with your feet flat on the floor, legs and ankles uncrossed, and your arm extended, palm up, on a table so that your elbow is positioned roughly at heart height.

Why? Crossing your legs, especially at the knee, temporarily raises blood pressure. If your feet or your arm are not supported, your muscles will contract. Even this small amount of isometric exercise can raise your blood pressure. Also, supporting your arm below or above the level of your heart may affect the accuracy of the reading.

Wait a few quiet minutes before taking a reading.

First, wrap the proper size cuff around your bare arm about an inch above the crook of your elbow. Sit quietly for a few minutes without distractions like TV, reading, phone scrolling, or talking. Then start the machine to take your blood pressure.

Why? Putting the cuff over clothes — or pushing up your sleeve so that it’s tight around your upper arm — may interfere with an accurate reading, though evidence on this is mixed. Ideally, you want to record blood pressure while feeling relaxed, not distracted, because even minor stress or tension can raise your blood pressure.

This video from the American Heart Association demonstrates the correct technique.

Why is diagnosing high blood pressure so important?

Nearly half of all adults have high blood pressure, but about a third of these people aren’t even aware they have the problem. An accurate diagnosis and treatment is vital, says Dr. Juraschek. Few things in medicine have shown such consistent results as the harms of high blood pressure, which is a major cause of heart attacks, strokes, kidney disease, and cognitive decline.

“It’s called the silent killer for a reason. We don’t feel or experience any of high blood pressure’s effects until it’s too late,” he says.

About the Author

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Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

photo of Howard E. LeWine, MD

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

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FITNESS HEALTH NATURAL-BEAUTY

Heat rash: How to spot it and what to do

A blazing yellow sun with sun rays against a yellow-red background with clouds; concept is heat-related illness

The first two weeks of July were the Earth’s hottest on human record, and people across the country continue to suffer from lingering, suffocating heat waves. The US Centers for Disease Control and Prevention has issued repeated warnings and tips about recognizing and preventing heat-related illnesses, like heat stroke, heat exhaustion, and heat cramps.

But one heat-related illness that people do not always recognize is heat rash.

“Heat rash can indicate that your exposure to excessive heat could lead to other serious heat-related issues, if not addressed,” says Dr. Abigail Waldman, a dermatologist with Harvard-affiliated Brigham and Women’s Hospital. "While heat rash is not dangerous in itself, sustained exposure to high heat can lead to heat exhaustion and heat stroke, so it's important to note any early signs that your body is struggling with the heat.”

What are the signs of heat rash?

Heat rash is also known as miliaria or prickly heat. It is caused when ducts from eccrine sweat glands that lead to the skin's surface are blocked or inflamed.

Eccrine sweat glands help your body maintain a steady temperature. When your internal temperature rises, these glands release water that rises to the surface of your skin through tiny ducts. There, it quickly evaporates, cooling your skin and the blood beneath.

However, sweat ducts may get blocked when you sweat excessively in hot temperatures, particularly if skin folds or tight-fitting clothes hinder their function.

Sweat is then trapped beneath the skin. This triggers inflammation, which leads to the appearance of small, itchy red bumps, similar to tiny pimples or blisters. In people with darker skin tones, these small, itchy bumps may not appear red, but will look slightly darker than surrounding skin.

Where and when is heat rash likely to occur?

Heat rash can appear on the neck, scalp, chest, groin, or elbow creases.

“Heat rash can occur any time the body sweats, so it is common in hot, humid climates, during hospitalizations, from fever, and during exercise,” says Dr. Waldman.

Heat rash also can occur in newborns, as their eccrine sweat glands are not fully developed. In newborns, heat rash looks like very thin blisters or water drops widely distributed on the face, trunk, arms, and legs. Call your pediatrician for advice if you notice a rash like this.

How can you treat heat rash?

Heat rash in adults is easy to treat with home remedies. “The techniques to relieve symptoms also can help prevent heat rash for adults and babies,” says Dr. Waldman.

  • Cool down. The first step is to get out of the heat and cool and dry your skin. Use a fan or air conditioner, take a cool shower, or apply cool compresses to the affected areas. It's important to know that some people are more vulnerable to heat, and to make plans to help stay safe when temperatures are dangerously high.
  • Prevent irritation. To prevent skin irritation, avoid wearing clothes made from synthetic materials, which can trap heat. (While dry-fit clothing helps to wicks away moisture from the skin, it often can be too tight fitting.) Instead, wear light, loose-fitting cotton clothing that allows airflow over your skin. If a heat rash occurs around your groin area, avoid wearing undergarments until it clears up.
  • Try anti-itch products. Use an over-the-counter topical corticosteroid cream or calamine lotion for itching. However, avoid baby powder, oily or greasy moisturizers, and sunscreen, as they can further block sweat ducts.

Heat rash typically goes away within one to two days once you cool down your body. More severe heat rashes can last a week or longer. See your doctor (or follow up with your pediatrician) if a heat rash has not cleared up after a week. Also seek immediate care if you experience pain, intense itching, or the rash appears infected.

About the Author

photo of Matthew Solan

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

photo of Howard E. LeWine, MD

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD