Editor-In-Chief: C. Michael Gibson, M.S., M.D. ;Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. ,Usama Talib, BSc, MD 
On the basis of temperature, heat stroke must be differentiated from heat wave, heat stress, heat exhaustion, hyperthermia and multi-organ dysfunction syndrome. Heat stroke is classified to 2 types: Exertional heat stroke (EHS) generally occurs in young individuals who engage in strenuous physical activity for a prolonged period in a hot environment and classic nonexertional heat stroke (NEHS) more commonly affects sedentary elderly individuals, persons who are chronically ill, and very young persons.
Heat related problems may be classified based on the temperature and the clinical presentation. The following table summarizes the related terms.
||Three or more consecutive days during which the air temperature is >32.2°C.
||Perceived discomfort and physiological strain associated with exposure to a hot environment, especially during physical work.
||Severe illness characterized by a core temperature >40°C and central nervous system abnormalities such as delirium, convulsions,
or coma resulting from exposure to environmental heat (classic heat stroke) or strenuous physical exercise (exertional heat stroke).
||Mild-to-moderate illness due to water or salt depletion that results from exposure to high environmental heat or strenuous physical
exercise; signs and symptoms include intense thirst, weakness, discomfort, anxiety, dizziness, fainting, and headache; core temperature
may be normal, below normal, or slightly elevated (>37°C but <40°C).
||A rise in body temperature above the hypothalamic set point when heat-dissipating mechanisms are impaired (by drugs or disease) or
overwhelmed by external (environmental or induced) or internal (metabolic) heat.
|Continuum of changes that occur in more than one organ system after an insult such as trauma, sepsis, or heat stroke.
Heat stroke is classified to 2 types.
- Exertional heat stroke (EHS) generally occurs in young individuals who engage in strenuous physical activity for a prolonged period in a hot environment.
- Classic nonexertional heat stroke (NEHS) more commonly affects sedentary elderly individuals, persons who are chronically ill, and very young persons.