As sweating continues, often at a rate of more than 1 liter per hour, the body loses lots of fluid. That can compromise heart and circulatory function and the ability to work. Heat cramps are involuntary muscle contractions caused by failure to replace fluids or electrolytes, such as sodium and potassium. Cramps can be relieved with stretching and by replacing fluids and electrolytes. Heat exhaustion is characterized by weakness, extreme fatigue, nausea, headaches, and a wet, clammy skin.
Heat exhaustion is caused by inadequate fluid intake.
It should be treated by resting in a cool environment and replacing fluids and electrolytes. Heat stroke is a medical emergency caused by failure of the body's heat controls. Sweating stops and the body temperature rises precipitously. Send for medical help at once and begin rapid cooling with ice or cold water, fanning the victim to promote evaporation. Treat for shock if necessary.