Heat stroke, also known as sun stroke, is a type of severe heat illness that results in a body temperature greater than 40.0 °C (104.0 °F) and confusion. Other symptoms include red skin, headache, and dizziness. There is generally a lack of sweating in classic heat stroke while sweating is generally present in exertional heatstroke. Onset can be sudden or gradual. Complications may include seizures, rhabdomyolysis, or kidney failure.
Heat stroke occurs because of high external temperatures or physical exertion. Risk factors include heat waves, high humidity, certain drugs such as diuretics, beta blockers, or alcohol, heart disease, and skin disorders. Cases not associated with physical exertion typically occur in those at the extremes of age or with long term health problems. Diagnosis is based on symptoms. It is a type of hyperthermia. It is distinct from a fever, where there is a physiological increase in the temperature set point.
Preventive measures include drinking sufficient fluids and avoiding excessive heat. Treatment is by rapid physical cooling of the body and supportive care. Recommended methods include spraying the person with water and using a fan, putting the person in ice water, or giving cold intravenous fluids. While it is reasonable to add ice packs around a person, this by itself is not routinely recommended.
Heat stroke results in more than 600 deaths a year in the United States. Rates have increased between 1995 and 2015. The risk of death is less than 5% in those with exercise-induced heat stroke and as high as 65% in those with non-exercise induced cases.