Heat-related illness is preventable, but more than 700 people die from extreme heat every year in the U.S., according to the Centers for Disease Control and Prevention. By understanding the warning signs of heat-related illness and learning how to prevent it, you'll be better prepared to reduce your risk.

What is heat-related illness?

Heat-related illness results from exposure to extreme heat where the body is unable to cool properly, causing a rapid rise in body temperature. Sweat normally removes body heat, but when humidity is high, sweat evaporates more slowly, preventing the body from releasing heat as quickly.

Serious conditions that can result from exposure to extreme heat include heat exhaustion and heat stroke.

• Heat exhaustion happens when fluids lost through sweat aren't adequately replenished. The victim may experience muscle cramping, headaches, nausea or dizziness.
• Heat stroke. Left untreated, heat exhaustion can progress to heat stroke, a serious and life-threatening condition. Systems of heat stroke include a body temperature of over 103°F, rapid pulse, confusion and loss of consciousness.

Although extreme heat can affect anyone, those with a greater risk of developing heat-related illness include very young children, adults over 65 and people with chronic conditions, such as diabetes and heart disease.

If you or someone nearby is experiencing any signs of heat-related illness, seek shelter in a cool, dry place and drink fluids. Call for medical assistance as quickly as possible.

Preventing heat-related illness

When it's hot and humid outside, take the following measures to reduce your risk of heat-related illness.

• Stay in air-conditioned indoor spaces as much as you can.
• Drink plenty of fluids, even if you're not thirsty.
• Limit outdoor activities, especially during the middle of the day when the sun is hottest.
• Pace your outdoor activities — start gradually and take plenty of breaks.
• When outdoors, wear loose, lightweight and brightly colored clothing and sunscreen.
• Do not leave children or pets in cars.

Check with family, friends or neighbors that may be at a greater risk for heat-related illness and stay up to date on local weather and safety conditions.