Heat exhaustion is one of the heat-related syndromes. These syndromes range in severity and seriousness from mild to potentially life-threatening. Other types of heat-related illnesses include heat rash, heat cramps, heat syncope and heatstroke.

Heat exhaustion can occur when your body loses too much water or salt — usually as a result of excessive sweating or dehydration. It can begin suddenly or happen over time, usually after working, exercising or playing in the heat.

Heat exhaustion signs and symptoms include:

  • Cool, moist skin with goose bumps when in the heat
  • Heavy sweating
  • Faintness
  • Dizziness
  • Fatigue
  • Weak, rapid pulse
  • Low blood pressure upon standing
  • Muscle cramps
  • Nausea or vomiting
  • Headache
  • Extreme thirst
  • Mild confusion
  • Decreased urine output

If you suspect heat exhaustion

Untreated, heat exhaustion can lead to heatstroke, which is a life-threatening condition. If you suspect heat exhaustion, take these steps immediately:

  • Move the person out of the heat and into a shady or air-conditioned place.
  • Lay the person down and elevate the legs and feet slightly.
  • Remove tight or heavy clothing.
  • Have the person sip chilled water, a decaffeinated sports drink containing electrolytes or other nonalcoholic beverage without caffeine.
  • Cool the person by spraying or sponging with cool water and fanning.
  • Monitor the person carefully.

Contact a health care provider if signs or symptoms worsen or if the person doesn't improve after taking first-aid measures.

Call 911 or your local emergency number if the person's condition gets worse, especially if he or she experiences:

  • Fainting
  • Agitation
  • Confusion
  • Seizures
  • Inability to drink
  • Core body temperature — measured by rectal thermometer — of 104 F (40 C) (heatstroke)

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April 15, 2022