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Symptoms and Signs of Heat Exhaustion

Doctor's Notes on Heat Exhaustion

Heat exhaustion is a condition that occurs when the body's cooling mechanism fails to maintain a normal core temperature and the body overheats. Causes of heat exhaustion can include strenuous work or exercise in a warm or hot environment, dehydration, alcohol intake, and wearing clothing that does not allow for evaporative cooling of the body.

Symptoms of heat exhaustion may include weakness, muscle cramps heavy sweating, headache, nausea, vomiting, weak and rapid pulse, thirst, clammy skin, dizziness, and elevated body core temperature (internal temperature, not skin temperature). Heat exhaustion can occur before the onset of heat stroke, which is a medical emergency. If there are signs or symptoms of heat stroke call 911 or get the person to a hospital’s emergency department immediately. Symptoms of heat stroke include that the body stops sweating, and the skin is hot and dry and sometimes reddish colored. Stroke-like symptoms including confusion, hallucinations, seizures, loss of consciousness, organ damage, coma, and death can occur in heat stroke if not treated promptly.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019

Heat Exhaustion Symptoms

Heat exhaustion in children occurs for the same reasons (causes) listed previously for adults, but children are more susceptible to dehydration. Symptoms of heat exhaustion may include:

  • fatigue,
  • nausea,
  • vomiting,
  • dehydration,
  • a headache,
  • clammy skin,
  • rapid breathing, and
  • irritability.

Treatment of heat exhaustion in children is similar to that of adults.

  • Put the child in the shade or an air-conditioned building
  • Loosen or remove tight or excessive clothing
  • Cool the child with evaporative cooling (mist skin with cool water and use fans) or give the child a cool (not cold) bath
  • Encourage Pedialyte or a sports drink
  • Seek medical care

If the child's body temperature reaches 105 F/40.5 C or above, or any other symptoms of heat stroke develop (such as the absence of sweating, seizures, lethargy or loss of consciousness), call 911 immediately. As in adults, untreated heat exhaustion in children may quickly progress to heat stroke and potentially death.

People with heat exhaustion may have some or all of these symptoms;

  • Weakness
  • Muscle cramps
  • Heavy sweating
  • Headache
  • Nausea and vomiting
  • Weak and rapid pulse
  • Thirst
  • Clammy skin
  • Dizziness and/or fainting

Individuals with heat exhaustion will generally have an elevated body core temperature (internal temperature, not skin temperature).

Heat Exhaustion Causes

The main cause of heat exhaustion is the failure of the body's cooling mechanism (mainly evaporative sweating) to maintain a normal core body temperature, resulting in the body overheating. This can occur in adults, children, and animals (dogs and cats, for example). Factors that can contribute to heat exhaustion include

  • strenuous work or exercise in a warm or hot environment,
  • dehydration,
  • alcohol intake, and
  • wearing clothing that inhibits evaporative cooling of the body.

The elderly and children under 5 years of age are at higher risk for developing heat exhaustion.

First Aid Emergencies What Heat Can Do to Your Body Slideshow

First Aid Emergencies What Heat Can Do to Your Body Slideshow

It's your natural cooling system. Your body pushes sweat out onto the surface of your skin. As the air absorbs it (evaporation), it draws heat away and cools you down. This works better in drier climates where humidity is low. You might get very tired and sometimes seriously ill if it doesn't work quickly enough.

REFERENCE:

Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.

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