Heat exhaustion is one of several types of heat disorders Overview of Heat Disorders Humans, who are warm-blooded animals, maintain their body temperature within 1 or 2 degrees of 98.6° F (37° C) as measured by mouth and 100.4° F (38° C) as measured rectally, despite large fluctuations... read more .
Heat exhaustion is more severe than heat cramps Heat Cramps Heat cramps are severe muscle spasms resulting from a combination of prolonged exercise, heavy sweating, and excessive water replacement in extreme heat. Heat cramps is a mild type of heat disorder... read more . Fluids and salts are more depleted, and symptoms are more severe. Heat exhaustion may progress to heatstroke Heatstroke Heatstroke is a life-threatening condition that results in very high body temperature and malfunction of many organ systems. (See also Overview of Heat Disorders.) Heatstroke can develop after... read more if people continue to be exposed to excessive heat.
Symptoms of heat exhaustion tend to be vague and similar to the symptoms of many other illnesses. People may not realize that their symptoms are related to the heat. Symptoms include
Muscle cramps may occur but often do not. People may feel faint or even lose consciousness when standing. Drenching sweats are common. The heart rate and breathing rate may become rapid. Blood pressure may become low.
Unlike in heatstroke Heatstroke Heatstroke is a life-threatening condition that results in very high body temperature and malfunction of many organ systems. (See also Overview of Heat Disorders.) Heatstroke can develop after... read more , confusion and incoordination do not occur in heat exhaustion. Also, body temperature is usually normal and if it is high, it is generally not higher than 104° F (40° C).
Heat exhaustion usually is diagnosed on the basis of the symptoms and occurrence after exposure to heat. Laboratory tests may be needed if doctors suspect a diagnosis other than heat exhaustion, or sometimes to measure the levels of sodium in the blood of people who may have drunk too much plain water.
Treatment of heat exhaustion involves rest (stopping activity), removing people from the hot environment, and replacing fluids and salts, either by mouth (with a sports drink or a solution of about 1 to 2 quarts of water containing 2 teaspoons of salt) or intravenously. Removing or loosening clothing and wetting the skin or applying wet cloths can also aid cooling.
After receiving fluids, people usually recover rapidly and fully.