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 F (40 C) or greater
• Changes in mental status or behavior, such as confusion, agitation, slurred speech
• Hot, dry skin or heavy sweating
• Nausea and vomiting
• Flushed skin
• Rapid pulse
• Rapid breathing
• Headache
• Fainting, which may be the first sign in older adults

Seek emergency medical care

If you suspect heatstroke, call 911 or your local emergency number. Then immediately move the person out of the heat, remove excess clothing, and cool him or her by whatever means available, for example:

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

Let the person drink cool water to rehydrate, if he or she is able. Don't give sugary, caffeinated or alcoholic beverages to a person with heatstroke. Also avoid very cold drinks, as these can cause stomach cramps.

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