Fainting and sweating: what to know

Cold, clammy sweating, nausea, warmth, or blurred vision can come before a reflex faint. Heavy sweating may also follow heat exposure, fluid loss, pain, fear, or a fall in blood sugar. A fast or irregular heartbeat, breathlessness, or sweating without a clear trigger can point to a heart or other medical problem. Dehydration and anaemia can make dizziness worse, while hypoglycaemia can cause sweating, trembling, weakness, and confusion.

Help the person lie flat away from traffic, stairs, and hot surfaces. Raise the legs when comfortable, keep the airway clear, and check that breathing is normal. Do not give food, drink, or tablets until they are fully awake. If they are alert and able to swallow, offer small sips of fluid; a person with known diabetes should follow their agreed low-sugar plan. Record the trigger, skin changes, palpitations, and recovery time.

Call emergency services if the person is not breathing normally, cannot be woken, has chest pain, severe shortness of breath, new neurological symptoms, a major injury, or repeated fainting. Seek urgent care for fainting during exertion, with an irregular heartbeat, or with ongoing sweating and confusion. A first faint, an unexplained event, or frequent near-faints should be reviewed promptly.

Ask whether blood pressure changes, glucose, blood count, medication effects, or an electrocardiogram should be checked. Describe whether sweating was hot or cold, whether you had eaten, and whether anyone saw abnormal movements.