Heat Cramps

Heat cramps are severe muscle spasms resulting from a combination of prolonged exercise, heavy sweating, and excessive water replacement in extreme heat.

During sweating, salts (electrolytes) and fluids are lost, but drinking large quantities of water dilutes the salts, causing cramps. Heavy sweating is most likely to occur on warm days, especially during strenuous exertion. Heat cramps are common among manual laborers, such as engine-room personnel, steelworkers, roofers, and miners. Heat cramps may also develop in athletes, especially mountain climbers or skiers, whose many layers of clothing may keep them from noticing their heavy sweating. Cramps are common in tennis players and runners who do not take time to replace salts lost in sweat.

Heat cramps are rhythmic contractions in muscles of the hands, calves, feet, thighs, or arms. The contractions cause muscles to become hard, tense, and painful.

Mild heat cramps can be treated by drinking beverages that contain salt or eating salty food. Severe heat cramps are treated with fluids and salts given intravenously.