By Mayo Clinic Staff

Heatstroke occurs when your body temperature rises rapidly and you're unable to cool down. It can be life-threatening by causing damage to your brain and other vital organs. It may be caused by strenuous activity in the heat or by being in a hot place for too long.

Heatstroke can occur without any previous heat-related condition, such as heat exhaustion. Heatstroke signs and symptoms include:

  • Fever of 104 degrees Fahrenheit (40 degrees Celsius) or greater
  • Changes in mental status or behavior, such as confusion, agitation and slurred speech
  • Hot, dry skin or heavy sweating
  • Nausea and vomiting
  • Flushed skin
  • Rapid pulse
  • Rapid breathing
  • Headache
  • Fainting
  • Seizure
  • Coma

Seek emergency medical care

If you suspect heatstroke, call 911 or your local emergency number. Then move the person out of the heat right away. Cool the person by whatever means available. For example:

  • Put the person in a cool tub of water or a cool shower.
  • Spray the person with a garden hose.
  • Sponge the person with cool water.
  • Fan the person while misting with cool water.
  • Place ice packs or cool wet towels on the neck, armpits and groin.
  • Cover the person with cool damp sheets.

If the person is conscious, offer chilled water, a sports drink containing electrolytes or other nonalcoholic beverage without caffeine.

Begin CPR if the person loses consciousness and shows no signs of circulation, such as breathing, coughing or movement.

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April 15, 2022