How to Take Blood Pressure at Home

Home blood pressure readings are often more useful than clinic readings. They are taken more often, in a calmer setting, and they catch the people whose pressure runs high only at the doctor's office and the people whose pressure runs high only everywhere else. Guidelines now treat a good home log as the standard for diagnosing and managing hypertension.

Good is the key word. A reading taken wrong is worse than no reading.

The cuff

Buy an upper arm cuff, not a wrist cuff. Wrist devices are sensitive to arm position and give inconsistent numbers. Finger devices are not accurate enough to use.

Buy one that has been independently validated. In the US, the list at validatebp.org is maintained by the American Medical Association. A validated device has been tested against a reference standard in a published protocol. Many popular models have not been.

Check the cuff size. Wrap it around your bare upper arm. The size range is printed on the cuff. A cuff that is too small reads high. Too large reads low. If your arm is above the standard range, order the large cuff. Most brands sell one.

Bring the device to a clinic visit once a year and have them compare it to their reading.

The setup

Do all of these. Each one that is skipped moves the number.

• No caffeine, exercise, or smoking for 30 minutes before.
• Empty your bladder.
• Sit in a chair with back support. Not a couch. Not the edge of a bed.
• Feet flat on the floor. Legs not crossed.
• Rest for five minutes. Sit quietly. No phone.
• Arm resting on a table so the cuff is at heart level. An arm hanging down reads high. An arm held up reads low.
• Cuff on bare skin, not over a sleeve. Bottom edge about an inch above the elbow crease.
• Do not talk during the reading. Talking adds points.

The schedule

Take two readings, one minute apart, in the morning before medication and food. Take two more in the evening before dinner. Do this for seven days. Discard the first day. Average the rest.

That is the protocol most guidelines use for a diagnosis. Afterwards, a few days a month is enough unless a clinician asks for more.

Record every reading. Most cuffs store them. Many sync to a phone. A paper log works.

The numbers

Blood pressure is written as two numbers. The top, systolic, is the pressure when the heart beats. The bottom, diastolic, is the pressure between beats. Both matter.

These are the American Heart Association and American College of Cardiology categories. Home readings are usually a few points lower than clinic readings, and some guidelines set home thresholds slightly lower to match.

A single reading in any category means little. The seven day average is what counts.

What to do with each result

Normal: recheck yearly, or every few months if you are over 40 or have risk factors.

Elevated or stage 1: talk to a clinician. The first treatment is usually changes to salt, weight, alcohol, and activity, with a recheck in a few months. Medication depends on overall risk.

Stage 2: see a clinician soon. Medication is usually started.

Over 180 or over 120: wait five minutes and take it again. If it is still there and you have chest pain, shortness of breath, back pain, numbness, weakness, vision change, or trouble speaking, call emergency services. If it is still there and you feel fine, call a clinician today.

Common mistakes

Reading right after walking in from outside. Reading with a full bladder. Reading with a phone in the other hand. Taking one reading, seeing a high number, and taking five more until a low one appears. The low one is not the true one. The average is.

If your home readings are consistently normal and clinic readings are consistently high, tell your clinician. That pattern has a name, white coat hypertension, and a validated home log is how it is diagnosed. The reverse pattern, normal in clinic and high at home, is called masked hypertension. It carries real risk and is only caught at home.