What should you know about low heart rate fainting?

Fainting, also called syncope, is a brief loss of consciousness caused by reduced brain blood flow. A slow pulse may result from the heart’s electrical system, medicines, or a response to pain, illness, or dehydration. A single reading does not explain the event by itself; the rate, rhythm, blood pressure, symptoms, and medical history all matter.

Anaemia, dehydration, and low blood sugar can also make fainting more likely. An irregular rhythm such as atrial fibrillation may cause palpitations or light-headedness, although a low-rate episode needs its own assessment.

If you feel faint, lie flat and raise your legs if you can. Loosen tight clothing, avoid driving, and tell someone what is happening. Once fully alert, sip fluids if you can drink safely. Arrange medical review, especially if the episode was new, followed an injury, or occurred during exertion. A clinician may check an ECG, blood pressure, medicines, and blood tests.

Call emergency services for fainting with chest pain, severe breathlessness, a sustained irregular heartbeat, seizure-like movements, serious injury, confusion, or failure to wake promptly. Seek urgent assessment if fainting occurs during exercise, while lying down, or repeatedly, or if a very slow pulse is accompanied by weakness or dizziness.

Ask whether your medicines or heart rhythm could be lowering your pulse, whether you need an ECG or monitor, and what pulse or symptoms should prompt urgent help. Mention what you were doing before the faint, warning symptoms, recovery time, and any family history of sudden cardiac problems.