Fainting because of heat

Hot conditions make the body send more blood toward the skin for cooling. Sweating also removes fluid and salts. After standing for a long time, exercising or entering a crowded hot place, the combined effect can cause weakness, headache, nausea, blurred vision and collapse. Dehydration is one possible contributor, but heat exhaustion, low blood sugar, anaemia and heart rhythm problems can also cause similar symptoms.

Move the person to a cool shaded place and lay them flat with their legs raised. Remove extra clothing and cool the skin with wet cloths or a fan. If they are awake and swallowing safely, offer small sips of cool water. Do not give drinks to someone who is confused or unconscious. Avoid returning to heat or strenuous activity until recovery is complete.

Call emergency services for confusion, a very hot body, seizure, breathing trouble, chest pain, severe headache, repeated vomiting or continuing unresponsiveness. Get prompt medical advice if recovery is incomplete, the faint followed exertion, or episodes recur. A first faint should be reviewed when the trigger is uncertain, particularly if there are medicines or health conditions affecting blood pressure.

Ask how to manage fluids in hot weather, whether any medicine increases heat or fainting risk, and whether your symptoms warrant blood pressure, blood tests or heart-rhythm checks.