Heart palpitations when hot: what to know

In hot weather or a warm room, sweating and widened blood vessels can reduce circulating fluid. The heart may beat faster to maintain blood flow, and dehydration can make the pounding or fluttering easier to notice. Heat, exertion, caffeine, alcohol, fever and anxiety can add to the sensation. Anaemia and an overactive thyroid can also make the heart work harder. An irregular rhythm such as atrial fibrillation is another possibility, so the setting alone cannot identify the cause.

Stop exertion and move to a cool place. Sip water, loosen tight clothing and rest while noticing whether the rhythm settles. Avoid more caffeine, nicotine and alcohol until you feel well. Record when it started, how long it lasted, whether the beat felt regular, and any heat exposure, illness or medicines. Repeated episodes deserve a clinician review, which may include a pulse check, blood tests or an electrocardiogram.

Call emergency services for palpitations with chest pain, severe breathlessness, fainting, confusion, blue or grey lips, or marked weakness. Seek prompt medical advice if episodes continue after cooling and rest, keep returning, or occur with swelling, breathlessness when lying down or known heart disease. Do not drive yourself if you feel faint.

Ask whether your symptoms could relate to dehydration, thyroid activity, anaemia or a rhythm problem, and whether you need an ECG or wearable monitor. Bring your episode notes and a list of medicines, supplements and stimulants.