Heat stroke

K K Jain MD (Dr. Jain is a consultant in neurology and has no relevant financial relationships to disclose.)
Originally released February 4, 2003; last updated January 24, 2020; expires January 24, 2023

This article includes discussion of heat stroke, atmospheric pyrexia, environmental hyperthermia, exertional heat illness, heat apoplexy, heat fever, heat-related illness, heatstroke, ictus solaris, and sun stroke. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Heat stroke is characterized by hyperpyrexia with core body temperature greater than 40°C (104°F) and neurologic dysfunction. Heat stroke is usually due to prolonged exposure to excessive atmospheric temperature but can also occur following prolonged exertion in athletes. It is distinct from fever due to disease. This article describes the pathophysiology, prevention, and management of heat stroke.

Key points


• Neurologic manifestations such as seizures and impairment of consciousness are the most prominent features of heat stroke when core body temperature exceeds 41°C.


• Apart from exposure to excessive heat, several diseases and drugs predispose to heat stroke.


• Rapid cooling by various measures is the most important part of management if temperature goes above 40°C.

Historical note and terminology

Heat stroke, also termed "sun stroke," is characterized by hyperpyrexia with core body temperature greater than 40°C (104°F) and neurologic dysfunction. Heat stroke is the only condition that is a true heat illness as there is clear evidence for a pathological elevation of the core body temperature, and it is recommended that terms such as “heat fatigue”, “heat exhaustion,” and “heat syncope” should be removed from the modern lexicon (Noakes 2008). As an environmental hyperthermia, heat stroke is distinct from fever due to disease. Heat stroke is a total breakdown of thermoregulation, and 2 classical forms have been described: (1) nonexertional, which occurs during heat waves without physical exertion, and (2) exertional heat stroke, which typically follows strenuous sports.

Heat stroke has been mentioned in the older medical literature under one name or another. Most of the studies of thermoregulation were conducted following introduction into the clinical practice of thermometry in the 19th century. Historical perspectives on thermoregulation have been reviewed elsewhere (Cooper 2002).

A notable victim of this condition was Sir Victor Horsley, the British pioneer of neurologic surgery, who met an untimely death during World War I from heat stroke at the age of 59 years (Tan and Black 2002).

The content you are trying to view is available only to logged in, current MedLink Neurology subscribers.

If you are a subscriber, please log in.

If you are a former subscriber or have registered before, please log in first and then click select a Service Plan or contact Subscriber Services. Site license users, click the Site License Acces link on the Homepage at an authorized computer.

If you have never registered before, click Learn More about MedLink Neurology  or view available Service Plans.

Find out how you can join MedLink Neurology