Why does heat stroke cause fever?

A fever from an infection is driven by the body's internal temperature setting. In heat stroke, external heat, exertion or both overwhelm cooling mechanisms such as sweating and blood flow to the skin. The temperature rise can injure tissues and affect the brain, heart and other organs. Fever is a common presentation of Heat Stroke, but fever also occurs with many illnesses unrelated to hot weather.

Treat suspected heat stroke as an emergency. Call emergency services, move the person into shade or air conditioning, remove extra clothing and cool the skin quickly with cool water, damp cloths and airflow. Wrapped cold packs can be placed at the neck, armpits and groin. Stay with the person and watch their breathing and alertness. Do not give fluids if they are confused, vomiting, drowsy or unable to swallow.

Emergency help is needed for high body temperature after heat exposure together with confusion, unusual behaviour, fainting, seizure, severe weakness or loss of consciousness. Call even if the person says they feel better after cooling. A child, older adult or person with a serious medical condition who becomes unwell in the heat should be assessed urgently.

Once recovered, ask about a safe return to outdoor activity and whether any medical conditions or medicines increase vulnerability to overheating. A clinician can help you plan breaks, cooling and fluids for your daily routine.