How common is fainting in heat stroke?

Heat stroke develops when the body cannot cool itself effectively. Core temperature rises and the nervous system can become affected, causing fainting, confusion, unusual behaviour, seizures, weakness, headache, nausea, or hot skin. Sweating may be present or absent. Fainting after strenuous activity or prolonged heat exposure is especially concerning.

A person who collapses in the heat may also have dehydration, heat exhaustion, a heart problem, or another cause of reduced consciousness. Do not wait for certainty at home: the combination of heat exposure and altered alertness needs emergency assessment.

Call emergency services. Move the person to shade or an air-conditioned place, remove excess clothing, and cool the skin with wet cloths, cool water, or fans while waiting. Place them on their side if they are unconscious but breathing. Do not give drinks to a person who is confused, drowsy, or unable to swallow safely.

Emergency help is needed for fainting with confusion, seizure-like movements, hot skin, severe headache, breathing problems, collapse during exertion, or failure to recover promptly. Keep cooling the person and monitor breathing. If breathing stops or is abnormal, follow the emergency dispatcher’s instructions.

After recovery, ask how heat exposure, fluid loss, medicines, or exertion may have contributed, when it is safe to return to activity, and how to recognise early heat illness.