Body temperature and heat exhaustion

Heat exhaustion develops when sweating and heat exposure outpace the body's ability to replace fluid. People may feel hot, weak, dizzy, thirsty, headachy, or unusually tired; excessive sweating and dark urine can point to fluid loss. A thermometer reading can vary with the measuring site and recent cooling, so consider the whole pattern rather than one result. Heat intolerance can make repeated episodes more likely and may deserve a separate medical review. Heat exhaustion can progress to heat stroke, especially when the person cannot drink or continues working in the heat.

Stop activity and move into shade or an air-conditioned place. Loosen clothing, cool the skin with damp cloths or a fan, and take frequent small sips of water or an oral rehydration drink if fully awake and not vomiting. Rest and avoid returning to heat until symptoms have settled. Monitor alertness and urine colour. If the person cannot keep fluids down, becomes confused, or fails to improve with cooling and rest, seek urgent help rather than continuing home care.

Call emergency services for confusion, fainting, seizure, collapse, severe breathing difficulty, or a rapidly worsening condition after heat exposure. Seek prompt assessment for persistent dizziness, repeated vomiting, very dark urine, or inability to drink. These features may reflect significant dehydration or a transition to heat stroke. People with heart, kidney, or other long-term conditions should seek advice earlier because fluid replacement may need individual guidance.

Ask which fluids are suitable, whether medicines affect heat tolerance, how long to rest before resuming activity, and what warning signs should trigger emergency care. Mention the exposure, symptoms, fluid intake, and any vomiting.