Hyperthermia

Hyperthermia is elevated body temperature due to failed thermoregulation that occurs when a body produces or absorbs more heat than it dissipates. Extreme temperature elevation then becomes a medical emergency requiring immediate treatment to prevent disability or death.

Common causes include heat stroke and adverse reactions to drugs. The former is an acute hyperthermia caused by exposure to excessive heat, or combination of heat and humidity, that overwhelms the heat-regulating mechanisms of the body causing uncontrollable elevation of body temperature. The latter is a relatively rare side effect of many drugs, particularly those that affect the central nervous system. Malignant hyperthermia is a rare complication of some types of general anesthesia.

Hyperthermia can be deliberately induced using drugs or medical devices and may be used to treat some kinds of cancer and other conditions, most commonly in conjunction with radiotherapy.

Hyperthermia differs from fever in that the body's temperature set point remains unchanged. The opposite is hypothermia, which occurs when an organism's temperature drops below that required to maintain normal metabolism.