Heat Stroke (Overheating of the Body)


Heat stroke is the most severe form of heat-related illness in which the core body temperature (the temperature inside the body) goes above 41.1°C. The human body can function optimally only when the core body temperature is maintained at 37°C. A rise in the core body temperature  results in a variety of heat-related illnesses ranging from dehydration and cramps to fainting, heat exhaustion and heat stroke.


Heatstroke is classified into the following two types:

  • Classic non-exertional heat stroke (NEHS): Sedentary elderly individuals, chronically ill persons or very young individuals are mostly affected by this type of heat stroke.
  • Exertional heat stroke: This affects individuals who engage in strenuous physical activity for long duration in very hot conditions.

Regardless of the type, a heat stroke could lead to multiple organ failure and death. Therefore, emergency medical help should be sought if heat stroke is suspected.


The following are the characteristic signs and symptoms of a heat stroke:

  • A body temperature above 40°C.
  • Absence of sweating is seen in NEHS, whereas sweating occurs in exertional heat stroke.
  • Neurological symptoms like delirium, confusion, seizures, coma are a hallmark of heat stroke
  • Rapid heart beat (tachycardia).
  • Rapid breathing (tachypnea) at more than 20 breaths per minute.


Classic non-exertional heat stroke is caused by heat waves in summer. The symptoms usually appear after a couple of days of exposure to the hot winds. Lack of cooling facilities (like air-conditioning) and dehydration (due to inadequate water intake) increases the chances of getting NEHS in hot summers.

Exertional heat stroke is caused by intense physical activity in a hot environment. The symptoms may appear within hours of exposure to the hot conditions. Excessive sweating and acute heat load due to intense physical activity increase the chances of developing exertional heat stroke.

Both types of heat strokes result from the inability of the body to manage the excess heat (caused by hot external conditions, intense physical activity, and loss of fluids) and maintain its core temperature around 37°C. An increase in the core body temperature damages the enzymes in all the cells. This results in widespread organ dysfunction that affects the brain, muscles, liver, kidneys, lungs, and heart. Widespread inflammation and blood clotting may also occur throughout the body.


Heat stroke has a high mortality rate. The chances of recovery depend on the age and physical condition of the patient. Immediate treatment is the critical factor in saving the lives of heat stroke patients. However, some of the patients show permanent brain or kidney damage even after recovering.

The following are the treatment options for heat stroke:

  • Rapid external cooling of the body is the first line of treatment that needs to be done immediately. This is done to reduce the core body temperature to near normal levels and prevent further damage to the brain and other organs. Rapid cooling methods include wetting with cool water, fanning, and massaging to increase the blood circulation. Ice packs can be applied in life-threatening cases.
  • Intravenous saline is given to rehydrate the patient.
  • Organ dysfunction is treated according to the symptoms. Benzodiazepine is used to prevent seizures. Blood transfusion (especially transfusion of platelets and plasma) might be given in cases of widespread clotting.

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