Heat syncope treatment: what to do after feeling faint

Heat can widen skin blood vessels while sweating reduces body fluid. Standing or walking may then reduce blood flow to the brain for a short time. The person may feel faint, pale, clammy or nauseated before briefly passing out. Recovery should begin after lying down, but fainting in heat can also overlap with heat exhaustion, a heart rhythm problem or another illness.

Help the person lie flat in a shaded or air-conditioned place and raise the legs if there is no injury. Loosen tight clothing and cool the skin with air, a cool cloth or a fan. Once fully awake and able to swallow, offer small sips of water. Do not give drinks to someone who is unconscious, confused or vomiting. Stay with them while they recover, and arrange medical advice if this was a first or repeated episode. A clinician may consider Anaemia, Atrial Fibrillation, Dehydration or Hypoglycaemia as possible contributors.

Call emergency services if the person remains unconscious, has abnormal breathing, chest pain, severe breathlessness, seizure-like movements, marked confusion or a significant fall. Urgent assessment is also needed if the skin is very hot, symptoms worsen, or recovery is not prompt. Avoid driving until a clinician has advised you after unexplained fainting.

Ask what may have triggered the episode, whether medicines need review, and whether blood pressure, blood tests or an electrical heart tracing are appropriate. Clarify when you can return to exercise, work in heat or driving.