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Synonyms of Hyperthermia

  • Heat-Related Illness
  • Heat Stress

Disorder Subdivisions

  • No subdivisions found.

General Discussion

Hyperthermia occurs when a person’s body temperature rises and remains above the normal; 98.6°F Most frequently, this occurs during the heat of summer and among the elderly. However, it may also be triggered by other medical conditions or certain medications.

Hyperthermia is sometimes induced as a palliative measure in the treatment of certain cancerous conditions.


Symptoms of hyperthermia include headache, nausea, fatigue, muscle cramps, thirst and profuse sweating, notwithstanding that the skin may feel cold and clammy. Without appropriate and prompt treatment to cool the body, hyperthermia may progress to more complicated and more dangerous conditions.


Hyperthermia is caused by heat. Hot summer weather, being out in the sun for too long a period of time, excessive exercise in the heat, over extended stays in a hot tub or sauna, or being in an overcrowded or overheated room without adequate ventilation can cause hyperthermia. Certain medications (particularly diuretics), alcoholic beverages, certain medical conditions and being overdressed in hot weather also causes hyperthermia. The inability to perspire sufficiently, high blood pressure or poor blood circulation may play an important role in susceptibility to hyperthermia.

Affected Populations

Hyperthermia affects males and females in equal numbers. It is common in people over 50 years of age, those confined to nursing homes, and people with other medical problems. Younger, healthy persons are rarely affected. Infants can also be affected by the heat since they cannot communicate their needs to others.

Related Disorders

The following disorders may be associated with hyperthermia.

Malignant Hyperthermia is a genetic disorder characterized by an abnormal response to certain anesthetic drugs. The patient normally shows no symptoms of discomfort or illness in everyday life. However if halothane or cyclopropane is given as an anesthetic in preparation for surgery, or a muscle relaxant such as succinylcholine is used, a life threatening high fever may be induced that can rise as high as 110 degrees F. (For more information on this disorder, choose "Malignant Hyperthermia" as your search term in the Rare Disease Database.)

Heat Exhaustion is caused by dehydration and loss of mineral salts from the body due to heat stress usually of three or more days duration. It is often seen in the elderly who are unaware of excessive water loss or are unable to replenish lost fluids. Elderly people taking diuretic drugs for hypertension are particularly prone to heat exhaustion.

Heat Stroke is a life-threatening condition requiring immediate treatment. It occurs mainly in the poor, the elderly, the chronically ill, alcoholics and patients with heart disease. Hot, humid weather usually precedes the onset of this condition. Body temperature of 104 F or above may be present leading, in extreme cases, to coma. Heat Stroke may be complicated by hemorrhage, jaundice, kidney failure, brain damage, peripheral neuropathy, or heart and lung damage. Survival depends on rapid reduction of body temperature, usually in a hospital. Illnesses involving dysfunction of the sweat glands, can be found in the Rare Disease Database by typing "Hyperhidrosis" as your search term.

Standard Therapies

Treatment of hyperthermia consists of cooling the body. Cool showers, use of fans or air conditioners, drinking plenty of fluids (excluding those that contain caffeine or alcohol) helps maintain the correct body temperature. Cool, slightly salty fluids may help restore body salts lost during sweating. People prone to hyperthermia should avoid being in the sun, wearing heavy clothing in hot, humid weather and staying out of overcrowded and under-ventilated environments.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010

For information about clinical trials sponsored by private sources, contact:

Hyperthermia Resources



Yoder E., Disorders due to heat and cold. In: Bennett JC, Plum F, eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA; W.B. Saunders Company. 1996;501-2.

Dale DC, The febrile patient. In: Bennett JC, Plum F, eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA; W.B. Saunders Company. 1996;1532.

Beutler B, Beutler SM, The pathogenesis of fever. In: Bennett JC, Plum F, eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA; W.B. Saunders Company. 1996;1533.

Prentice HG, et al., Liposomal amphotericin B for fever and neutropenia. N Engl J Med. 1999;341:1152-53.

Rakita R, Liposomal amphotericin B for fever and neutropenia. N Engl J Med. 1999;341:1153-54.

The information in NORD’s Rare Disease Database is for educational purposes only. It should never be used for diagnostic or treatment purposes. If you have questions regarding a medical condition, always seek the advice of your physician or other qualified health professional. NORD’s reports provide a brief overview of rare diseases. For more specific information, we encourage you to contact your personal physician or the agencies listed as “Resources” on this report.

Report last updated: 2007/08/07 00:00:00 GMT+0

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