Heat exhaustion

Heat exhaustion occurs when a person cannot sweat enough to cool the body. It generally develops when a person is working or exercising in hot weather, sweats a lot, and does not drink enough liquids to replace those lost fluids. Heat exhaustion can be caused by loss of fluid (dehydration) or loss of electrolytes.

Symptoms of heat exhaustion include fatigue, weakness, headache, dizziness, or nausea, and the skin is pale, cool, and moist. Mild heat exhaustion does not cause a decrease in a person's mental alertness, but it may occasionally cause fainting. Mild cases of heat exhaustion usually can be treated at home.

Moderate to severe heat exhaustion can sometimes lead to heatstroke, which requires emergency treatment.