Heat exhaustion: First aid

By Mayo Clinic Staff

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

Heat exhaustion can happen when the body loses too much water or salt — usually because of heavy sweating or dehydration. It can begin suddenly or happen over time, usually after working, exercising or playing in the heat.

Heat exhaustion symptoms include:

  • Cool, moist skin with goose bumps when in the heat.
  • Heavy sweating.
  • Faintness.
  • Dizziness.
  • Fatigue.
  • Weak, rapid pulse.
  • Low blood pressure after standing up.
  • 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 raise the legs and feet slightly.
  • Remove tight or heavy clothing.
  • Have the person sip chilled water, a sports drink containing electrolytes or another nonalcoholic beverage without caffeine.
  • Cool the person by spraying or sponging with cool water and fanning.
  • Monitor the person carefully.

Contact a healthcare professional if symptoms get worse 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 the person:

  • Faints.
  • Becomes agitated.
  • Is confused.
  • Has a seizure.
  • Is not able to drink.
  • Has a core body temperature — measured with a rectal thermometer — of 104 degrees Fahrenheit (40 degrees Celsius), which indicates heatstroke.
March 06, 2024