Your body stays cool by sweating. This releases heat through your skin. But spending a long time in high temperatures can cause this cooling system to fail. When this happens, you stop sweating. Your body temperature may rise to very high levels. In severe cases, your brain and other vital organs may shut down. This is known as heatstroke.

Unless your body is cooled, death can occur in minutes. Heatstroke can happen in young athletes doing intense workouts outside in hot weather. This is called exertional heatstroke. It can happen to older adults or other vulnerable people who have no air conditioning during a heat wave. This is called nonexertional or classic heatstroke.

Symptoms include:

• Confusion.
• Fainting.
• A body temperature of 104°F (40°C) or higher.
• Hot, dry skin.
• Nausea and vomiting.
• A rapid heartbeat.
• Quick, shallow breathing.
• Loss of balance and coordination.
• Seizures.
• Flushed skin.

Heatstroke is a medical emergency.

Call 911 right away.

While waiting for help, take immediate action to cool the overheated person:

• Get the person away from the heat source and indoors or into shade.
• Remove excess clothing. But don't delay the cooling process in order to remove all clothing or equipment. Start the cooling process first. Clothing and equipment can be removed after you start cooling the person.
• Cool the person with whatever means available. Put them in an ice tub, a cool tub of water, or a cool shower (as long as the person's mouth and nose can be kept from being underwater). Or spray them with a garden hose, sponge them with cool water, or fan them while misting them with cool water. Or place ice packs or cold, wet towels on the person's head, neck, armpits, and groin. Change the towels and sheets when they're no longer cool.
• Continue the cooling process until help arrives, or until the person starts to shiver.

• To cool the body, lukewarm water may be sprayed over the body, and large fans may be used to blow air over the damp skin. Ice packs wrapped in cloth may be put on the neck, armpits, and groin. Or the person may be put in an ice water bath.
• I.V. fluids will likely be given. These help cool the body and replace fluids.
• Blood and urine tests will likely be done. These can help find damage to organs, especially the kidneys.