Heart palpitations out of nowhere: what to know

Palpitations may follow caffeine, nicotine, alcohol, stress, lack of sleep, fever, dehydration or a drop in blood sugar. They can feel like pounding, fluttering, skipped beats or a sudden racing pulse. The sensation alone cannot distinguish a temporary response from a heart-rhythm change.

A clinician may check for anaemia, iron deficiency anaemia, hyperthyroidism and atrial fibrillation. Heart failure is another condition worth discussing when palpitations occur with breathlessness, swelling or unusual tiredness. Record what you were doing and whether the pulse felt steady or uneven.

Sit down, breathe slowly and avoid driving while you feel unwell. Stop exercise, caffeine and nicotine for the moment; sip water if dehydration is possible. Write down the start and end of the episode, your pulse if you can check it safely, and symptoms such as dizziness or chest discomfort.

Book a medical appointment when episodes repeat, last longer than expected, or occur without a clear trigger. An ECG, blood tests and sometimes a longer rhythm recording can help connect the sensation with the heartbeat.

Call emergency services if palpitations come with chest pain or pressure, severe difficulty breathing, fainting, collapse, confusion or sudden one-sided weakness. Seek prompt advice for a fast or irregular rhythm that does not settle, or for new symptoms in someone with known heart disease.

Ask what tests fit the episode pattern, whether a wearable monitor is useful, and whether thyroid, blood-count or glucose testing is appropriate. Bring a list of medicines, inhalers, supplements and energy products, including when you take them.