Heat stress, heat fatigue, heat syncope (sudden dizziness after exercising in the heat, heat cramps and heat exhaustion are all forms of "hyperthermia," the general name given to a variety of heat-related illnesses. Symptoms may include headache, nausea, muscle spasms and fatigue after exposure to heat. If you suspect someone is suffering from a heat-related illness:

• Get the victim out of the sun and into a cool place, preferably one that is air-conditioned.
  
  
• Offer fluids but avoid alcohol and caffeine. Water, fruit and vegetable juices are best.
  
  
• Encourage the individual to shower, bathe or sponge off with cool water.
  
  
• Urge the person to lie down and rest, preferably in a cool place.

Heat stroke is especially dangerous for older people and requires emergency medical attention. A person with heat stroke has a body temperature above 104 and may have symptoms such as confusion, combativeness, bizarre behavior, faintness, staggering, strong rapid pulse, dry flushed skin, lack of sweating, possible delirium or coma.

The temperature does not have to hit 100 for a person to be at risk for hyperthermia. Both an individual's general health and/or lifestyle may increase the threat of a heat-related illness. Health factors which may increase risk include:

• Age-related changes to the skin such as poor blood circulation and inefficient sweat glands.
  
  
• Heart, lung and kidney diseases, as well as any illness that causes general weakness or fever.
  
  
• High blood pressure or other conditions that require changes in diet. For example, people on salt restricted diets may increase their risk. However, salt pills should not be used without first asking a consulting doctor.
  
  
• The inability to perspire caused by medications including diuretics, sedatives, tranquilizers and certain heart and blood pressure drugs.
  
  
• Taking several drugs for various conditions. It is important, however, to continue to take prescribed medication and discuss possible problems with a physician.
  
  
• Being substantially overweight or underweight.
  
  
• Drinking alcoholic beverages.

Lifestyle factors also can increase risk, including extremely hot living quarters, lack of transportation, overdressing, visiting overcrowded places and not understanding weather conditions. Older people, particularly those at special risk, should stay indoors on especially hot and humid days, particularly when there is an air pollution alert in effect. People without fans or air conditioners should go to shopping malls, movie houses and libraries. Friends or relatives might be asked to supply transportation on particularly hot days. Many communities, area agencies, religious groups and senior citizen centers also provide such services as cooling centers.

For a free copy of the National Institute on Aging's AgePage on hyperthermia and other important health information, please contact the NIA Information Center at 1-800-222-2225 or go to http://www.niapublications.org/agepages/hyperther.asp. The NIA is part of the Department of Health and Human Services' National Institutes of Health. The NIA is the lead federal agency supporting and conducting biomedical, social, and behavioral research and training related to aging and the diseases and special needs of older people.

The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.