Heat exhaustion and heatstroke require different responses. Heat exhaustion develops first and shows signs including heavy sweating, weakness, dizziness, nausea, headache, and muscle cramps. Move the person to a cool place, lie them down with legs elevated, give them water to drink, and cool their skin with cool water or damp cloths. They should recover within 30 minutes.
Heatstroke is more serious and occurs when the body temperature rises dangerously high. Signs include no sweating despite heat, confusion, loss of consciousness, seizures, and a temperature above 40 degrees Celsius. This is a medical emergency. Call emergency services immediately. While waiting, move the person to a cool place and cool their skin with water, ice packs, or cold cloths. Do not give them anything to drink if they are unconscious.
Prevention matters most. Avoid peak heat hours, drink plenty of water, wear light clothing, and check on vulnerable people like the elderly and young children during hot weather. Never leave anyone in a parked car.