The symptoms are painful muscle spasms. Care for heat cramps with rest and fluid intake. Do not take salt tablets. Activity can resume when the cramps subside, but fluid intake should continue. Less dangerous than heat stroke, heat exhaustion typically occurs when people exercise heavily or work in a warm, humid place where body fluids are lost through heavy perspiring.
Fluid loss causes blood flow to decrease in the vital organs, resulting in a form of shock.
With heat exhaustion, perspiration does not evaporate as it should because of high humidity or too many layers of clothing. As a result, the body is not cooled properly. Body temperature will be near normal. The victim's temperature control system, which produces perspiration to cool the body, stops working. The body temperature can rise so high that damage and death may result if the body is not cooled quickly.