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uk Health & medical scares heart racing at rest • heart pounding suddenly • palpitations while resting • rapid heartbeat episode • fast pulse sitting down • fluttering in chest • irregular heartbeat feeling • sudden tachycardia at rest • pounding heartbeat lying down • skipped beats sensation • new heart palpitations • lightheaded with palpitations • dizzy during rapid heartbeat • shortness of breath and palpitations • chest pain with palpitations • anxiety-like heart symptoms • unexplained fast heartbeat • resting heart rate feels high • sudden pounding heart at night

What to do if…
your heart suddenly starts racing or pounding while you are at rest

By PanicStation.org Reviewed under our editorial policy Last reviewed: UK guide

Short answer

Stop what you’re doing, sit or lie down, and check for red-flag symptoms. If you have chest pain, shortness of breath, dizziness/lightheadedness, or fainting/near-fainting, call 999.

Do not do these things

  • Do not drive yourself to A&E or “push through it”.
  • Do not take extra doses of heart/blood pressure medicines, aspirin, or someone else’s medication “just in case”.
  • Do not try to “burn it off” with exercise.
  • Do not add stimulants right now (energy drinks, lots of caffeine, nicotine, recreational drugs).
  • Do not take new “cold/flu” medicines to self-treat (some can worsen palpitations), unless a pharmacist/clinician advises it for you.
  • Do not ignore it if this is new, happens at rest, or keeps recurring.

What to do now

  1. Get stable first. Sit with back support or lie down. If you feel faint, lie flat and raise your legs slightly.
  2. Red-flag check — call 999 or go to A&E now if you have palpitations with any of these:
    • Chest pain/pressure (including pain spreading to arm/jaw/back)
    • Shortness of breath
    • Feeling dizzy or lightheaded
    • Fainting or feeling like you might faint
  3. If no red flags, capture what’s happening (this helps clinicians).
    • Note the time it started and what you were doing.
    • Feel your pulse at your wrist/neck: does it feel regular or irregular?
    • If you can, count beats for 30 seconds and write the number down.
    • If you have a smartwatch/fitness tracker, save the reading (and any ECG recording if you already know how to do it safely).
  4. Reduce strain for the next 10–15 minutes.
    • Loosen tight clothing. Avoid standing up quickly.
    • Breathe slowly and steadily.
    • Sip water if you may be dehydrated (skip if it makes nausea worse).
    • Stop caffeine/nicotine/alcohol for now.
  5. Only use a clinician-taught technique if you’ve been taught it before.
    • If you’ve previously been taught a manoeuvre for episodes of fast, regular rhythm, use only what you were taught — and only if you feel otherwise well (no chest pain, no breathlessness, no dizziness/near-fainting).
    • If you haven’t been taught one, don’t experiment. Move to step 6.
  6. Get the right level of help based on how it’s going.
    • If it’s still happening (even without red flags), call NHS 111 (or use 111 online) for urgent advice.
    • If it’s stopped but this was new, unusually strong, lasted more than a few minutes, or keeps coming back, ask your GP surgery for an urgent appointment or contact 111.
  7. Seek urgent advice sooner if you’re higher risk. For example: known heart disease/arrhythmia, pregnancy/postpartum, recent procedure, severe infection/fever, significant dehydration, or medication changes that affect heart rhythm.

What can wait

  • You don’t need to work out the exact cause right now.
  • You don’t need to decide today about long-term tests or treatment.
  • You don’t need to keep re-checking your pulse repeatedly once you’ve noted the key details.

Important reassurance

A sudden pounding or racing heartbeat can feel frightening even when it settles. Taking calm, practical steps and using the red-flag check is a sensible way to stay safe and get appropriate help.

Scope note

This covers first steps for the first minutes/hours. If episodes recur, clinicians may recommend ECG monitoring and blood tests, and review medicines and triggers.

Important note

This is general information, not a diagnosis. If you think you’re having a medical emergency or you feel seriously unwell, call 999.

Additional Resources

About this guide

PanicStation.org guides are written as plain-English first steps, then reviewed for clarity, jurisdiction, and source quality. If you notice an error, outdated information, unclear wording, or a broken link, please contact us.

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