Complications of Heat Exhaustion

Heat exhaustion develops when the body loses fluid and salt through sweating faster than they are replaced. Excessive sweating, thirst, headache, dizziness, weakness and heat intolerance may occur. Dehydration can reduce circulation and affect concentration, balance and kidney function; dark urine can be a sign that the body is conserving fluid. If heat exposure continues or the person cannot drink, the condition may progress to heat stroke, which can impair the brain and other organs. Symptoms should improve with prompt cooling and appropriate fluids.

Move to shade or an air-conditioned place, loosen clothing and cool the skin with wet cloths, fans or a cool shower. Give small, frequent sips of water or an appropriate rehydration drink if the person is awake and able to swallow. Stop exercise and avoid returning to heat until fully recovered. If symptoms do not improve promptly, or vomiting prevents drinking, arrange medical assessment. Never leave an unwell person alone in a hot environment.

Call emergency services for confusion, fainting, seizures, loss of coordination, severe weakness, inability to drink, worsening symptoms or a very hot body with altered behaviour. These signs raise concern for heat stroke rather than uncomplicated heat exhaustion. Emergency help is also needed when the person becomes less alert or stops sweating while remaining overheated. Begin cooling while waiting, but do not delay transport to seek drinks or medication.

Ask whether dehydration needs treatment, when it is safe to return to exercise or outdoor work, how to replace fluids during future heat exposure, and whether medicines or health conditions increase your risk.