Heart racing while resting

A resting heartbeat can feel forceful after caffeine, nicotine, alcohol, emotional strain, fever, poor sleep, or a new medicine. Dehydration, hypoglycaemia, anaemia, iron deficiency anaemia, and hyperthyroidism can also produce a racing sensation. Atrial fibrillation may cause an uneven pulse, while heart failure may be associated with breathlessness, swelling, or reduced exercise tolerance. A symptom alone cannot distinguish these causes.

Stop activity, sit comfortably, and breathe at a steady pace. Check whether the pulse feels regular or irregular and write down the start and end of the episode. Review recent caffeine, alcohol, supplements, illness, and medicine changes, but do not stop prescribed treatment without advice. Book a medical appointment when episodes recur, last longer, or occur without an obvious trigger.

Call emergency services for chest pressure, severe breathlessness, fainting, collapse, new confusion, or severe weakness with palpitations. Seek urgent assessment if the racing or irregular heartbeat continues at rest or is accompanied by dizziness. Testing may include an ECG, blood count, thyroid testing, glucose, and longer heart-rhythm monitoring.

Ask whether your pulse pattern needs an ECG or monitor, whether blood tests could explain it, and which triggers or medicines deserve attention.