Heatstroke is similar to heat cramps and heat exhaustion. It's one of the heat-related problems that often result from heavy work in hot environments, usually accompanied by inadequate fluid intake. Older adults, people who are obese and people born with an impaired ability to sweat are at high risk of heatstroke. Other risk factors include dehydration, alcohol use, cardiovascular disease and certain medications.

What makes heatstroke much more severe and potentially life-threatening is that the body's normal mechanisms for dealing with heat stress, such as sweating and temperature control, are lost. The main sign of heatstroke is a markedly elevated body temperature — generally greater than 104 F — with changes in mental status ranging from personality changes to confusion and coma. Skin may be hot and dry, although in heatstroke caused by exertion, the skin is usually moist.

Other signs and symptoms may include:

• Rapid heartbeat
• Rapid and shallow breathing
• Elevated or lowered blood pressure
• Cessation of sweating
• Irritability, confusion or unconsciousness
• Fainting, which may be the first sign in older adults

If you suspect heatstroke:

• Move the person out of the sun and into a shady or air-conditioned space.
• Dial 911 or call for emergency medical assistance.
• Cool the person by covering him or her with damp sheets or by spraying with cool water. Direct air onto the person with a fan or newspaper.