Irregular Heartbeat Flag on a BP Monitor: What to Do Next
An irregular heartbeat blood pressure monitor flag, seen on a home device, is a prompt to retake the reading properly, not a diagnosis. Most flags come from a reading taken while moving, talking, or with a loose cuff, so the first job is to measure again the right way. The second job is to notice whether the flag keeps coming back.
At a glance
- What the flag is: the monitor noticed that the pulse between beats was not steady during that reading
- What to do first: sit quietly for a few minutes, then take another reading after one minute
- Keep: the date, time, and how often the flag appears, in the same log as your blood pressure
- See a GP: if the flag keeps appearing or your pulse feels irregular on most days
- Quotable rule: one flag is a reason to measure again, and a repeated flag is a reason to speak to a doctor
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What does an irregular heartbeat flag actually mean?
The flag means the monitor detected a pulse pattern that was not steady during that reading. It does not say what caused the pattern. Short, harmless changes in rhythm happen, and a loose cuff, a moving arm, or a full stomach can produce the same flag. A pulse that stays irregular across several calm readings is different, and that is when a clinician should look at it.
The symbol for the flag differs by model. Check your own instruction manual to see what your monitor shows, rather than guessing from an icon in an article or a friend’s photo.
How do I retake a reading properly, step by step?
Follow your monitor’s own instructions, which set the cuff size, the arm, and the number of readings. The steps below are the usual pattern for an upper-arm monitor.
- Sit quietly for a few minutes before measuring, with your back supported and both feet flat on the floor.
- Rest the arm on a table so the cuff sits at heart level, with the sleeve pushed up and no tight clothing.
- Do not talk, cross your legs, or move during the reading.
- Check that the cuff tube is pushed fully into the monitor and that the cuff is snug but not cutting into the skin.
- Start the reading and wait without moving until the monitor shows the result.
- Wait one minute, then take a second reading the same way. Follow your doctor or nurse on how many readings to take in total.
- Count your pulse by hand for thirty seconds, then multiply by two, and compare it with the monitor’s pulse figure.
- Write down all the readings, the flag if it appeared, and the time.
How do I record the flag so a doctor can use it?
A doctor learns more from a pattern over several weeks than from one reading. Keep a simple log with the date, the time, the blood pressure numbers, the pulse, and a tick if the flag appeared. Add a short note if you had just walked, climbed stairs, drunk coffee, or felt anxious.
Try this
Take readings at the same time of day, at the same chair, with the same arm. Consistent conditions make a real pattern much easier to see, and make a chance flag easy to recognise.
What can throw off the flag?
- Talking, laughing, or moving during the reading
- A loose cuff, or a cuff put on over clothing
- A cold hand or a cold room, which can change the pulse signal
- A recent walk, climbing stairs, or a hurried trip to the bathroom
- Caffeine, a large meal, or strong emotion just before measuring
- Using the wrong cuff size for your arm
A flag tells you the reading was not clean enough to trust, and a repeated flag tells you to ask a clinician.
When should I take the flag to a doctor?
The NHS advises seeing a GP if you think you may have symptoms of atrial fibrillation, or if you have heart palpitations that keep happening or are getting worse. For blood pressure, the NHS says it is “usually considered high” at “135/85 or higher when checked at home” and at “140/90 or higher when checked by a healthcare professional.” Bring your log, not just the last reading, so the doctor can see the pattern and the context.
Irregular pulse can be linked to atrial fibrillation, and the NHS describes it as “a type of heart rhythm problem where your heartbeat is not steady.” Many people have no symptoms and find it at a check-up. A monitor flag cannot confirm or rule that out, so the next step is a clinic check, not a home conclusion.
What should I do if I feel unwell during the reading?
Stop the reading and sit or lie down. If you have a fast or irregular heartbeat with chest pain, shortness of breath, fainting or dizziness, or confusion or difficulty speaking, call 999 now. For stroke signs such as weakness or numbness on one side, a drooping face, vision problems, or a severe headache, also call 999 now. The NHS says not to drive yourself to A&E, and the person you speak to at 999 will advise you on what to do.
Speak to a GP if the irregular heartbeat flag keeps coming back across calm readings, if you feel a racing or uneven pulse on most days, or if you have a known heart rhythm problem and the flag changes. Call 999 for the warning signs listed above, even if the flag has come and gone before. Do not start, stop, or change any medicine because of a monitor flag. Your prescriber decides that after reviewing your readings.
Frequently asked questions
What does irregular heartbeat mean on a blood pressure monitor?
It means the pulse was not steady during that reading. It is a prompt to measure again properly, not a diagnosis.
Why does my blood pressure monitor show irregular heartbeat?
Common causes include talking or moving during the reading, a loose cuff, or a recent walk. A repeated flag across calm readings is the one that needs a clinician to look at it.
Can a blood pressure monitor detect irregular heartbeat?
Some monitors do flag an irregular pulse during a reading. The flag is a screening signal, so it cannot confirm atrial fibrillation on its own.
What should I do when the irregular heartbeat flag appears?
Sit quietly for a few minutes, check the cuff, and take another reading after one minute without talking. Write down the results and the time.
How many irregular flags mean I should see a doctor?
There is no set number. A flag that keeps returning across several calm readings, or a pulse that feels irregular on most days, is a good reason to see a GP.
What do the symbols on my monitor mean?
Symbols differ by model. Check your instruction manual, since guessing from a picture can lead to the wrong conclusion.
Is an irregular heartbeat flag the same as atrial fibrillation?
Not necessarily. The flag is a sign that the pulse was uneven during that reading. Only a clinical check, often with an ECG, can say whether atrial fibrillation is present.
Should I stop my medicine if the monitor shows a flag?
No. Do not start, stop, or change any medicine because of a monitor flag. Talk to your prescriber or pharmacist first.
What is the best time of day to check the readings?
The NHS says readings are usually taken twice daily, once in the morning and once in the evening. Keep the same times each day, and follow the schedule your doctor or nurse sets.
For the normal home reading method, read how to check blood pressure at home the right way. To understand gaps between home and clinic numbers, see home BP reading vs clinic errors. If the racing-heart feeling is what you notice, see palpitations and the racing heart. For the full list of stroke warning signs, see stroke symptoms and BE FAST. Explore the Diabetes and Blood Pressure hub.