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Causes
By Mayo Clinic staffYour body's heat combined with environmental heat results in what's called your core temperature — your body's internal temperature. Your body needs to regulate the heat gain (and in cold weather, heat loss) from the environment to maintain a core temperature that's normal, approximately 98.6 F (37 C).
Impaired cooling mechanism
In hot weather, your body cools itself mainly by sweating. The evaporation of your sweat regulates your body temperature. However, when you exercise strenuously or otherwise overexert in hot, humid weather, your body is less able to cool itself efficiently.
As a result, your body may develop heat cramps, the mildest form of heat-related illness. Signs and symptoms of heat cramps usually include heavy sweating, fatigue, thirst and muscle cramps. Prompt treatment usually prevents heat cramps from progressing to heat exhaustion.
You usually can treat heat cramps by drinking fluids containing electrolytes (such as Gatorade or other sports drinks), getting into cooler temperatures, such as an air-conditioned or shaded place, and resting.
Other causes
Besides hot weather and strenuous activity, other causes of heat exhaustion include:
- Dehydration, which impedes your body's ability to sweat and maintain a normal temperature
- Alcohol use, which can affect your body's ability to regulate your temperature
- Overdressing, particularly in clothes that don't allow sweat to evaporate easily
- Heat exhaustion. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/print/sec21/ch318/ch318c.html. Accessed Sept. 2, 2009.
- Extreme heat: A prevention guide to promote your personal health and safety. Centers for Disease Control and Prevention. http://www.bt.cdc.gov/disasters/extremeheat/heat_guide.asp. Accessed July 7, 2009.
- Zimmerman JL, et al. Hyperthermia. In: Hall JB, et al. Principles of Critical Care. 3rd ed. New York, N.Y.: McGraw-Hill Professional; 2005. http://www.accessmedicine.com/content.aspx?aID=2282701. Accessed July 7, 2009.
- Mechem CC. Severe hyperthermia in adults: Heat stroke and malignant hyperthermia. http://www.uptodate.com/home/index.html. Accessed Aug. 18, 2009.
- Hyperthermia: Too hot for your health. National Institute on Aging. http://www.nia.nih.gov/HealthInformation/Publications/hyperthermia.htm. Accessed July 7, 2009.
- Bouchama A, et al. Heat stroke. New England Journal of Medicine. 2002;346:1978.
