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

What to do now

1. Get stable first. Sit with back support or lie down. If you feel like you might pass out, lie flat and raise your legs slightly.
2. Call 911 now if any emergency warning sign applies right now:
   • Chest pain, chest pressure, or pain spreading to your arm, jaw, back, neck, or stomach
   • Severe shortness of breath, or you cannot speak full sentences
   • Fainting, near-fainting, severe dizziness, or loss of alertness
   • Sudden weakness, confusion, cold sweating, or feeling too unwell to stay upright
3. Capture a few useful details while you are still and safe:
   • Note the start time, what you were doing, and anything you took in the last few hours, including caffeine, alcohol, cannabis, stimulants, cold medicines, supplements, or new prescriptions.
   • Check your pulse if you can do it calmly. Notice whether it feels regular or irregular. Count for 30 seconds and double the number, or count for 60 seconds if that is easier.
   • If you have a smartwatch or fitness tracker, save the reading and any ECG recording if you already know how to use that feature safely.
4. Reduce strain for the next few minutes:
   • Loosen tight clothing.
   • Avoid standing up quickly.
   • Breathe slowly and steadily.
   • Sip water if you may be dehydrated and it does not worsen nausea.
5. Only use a clinician-taught technique if you have been taught it before. If a clinician previously taught you a maneuver for episodes of fast, regular rhythm, use only what you were taught, and only if you feel otherwise well. Do not try it if you have chest pain, breathlessness, dizziness, or near-fainting.
6. If it is not an emergency but the racing or pounding continues, seek same-day medical advice. Use urgent care, telehealth, your doctor’s on-call line, or your health plan’s nurse line. If you feel worse, unsafe, or unsure, go to an Emergency Department or call 911.
7. If it stops but this was new, unusually strong, did not settle quickly, or keeps coming back, arrange prompt medical evaluation.
8. Seek care sooner if you have higher-risk context, such as known heart disease, a known rhythm problem, pregnancy or recent postpartum period, recent surgery, severe infection or fever, significant dehydration, stimulant medication changes, or a history of fainting with palpitations.