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Related to heat hyperpyrexia: heat exhaustion
A severe and often fatal illness produced by exposure to excessively high temperatures, especially when accompanied by marked exertion; characterized by headache, vertigo, confusion, hot dry skin, and a slight rise in body temperature; in severe cases, high fever, vascular collapse, and coma develop.
a severe and sometimes fatal condition resulting from failure of the temperature-regulating capacity of the body, caused by prolonged exposure to sun or to high temperature. Reduction or cessation of sweating is sometimes an early symptom. Body temperature of 105° F or higher, tachycardia, hot and dry skin, headache, altered mental status, and seizures may occur. Treatment includes cooling, sedation, and fluid replacement. Also called heatstroke, sunstroke, thermic fever. See also hyperpyrexia. Compare heat exhaustion.