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Hyperthermia: Too Hot for Your Health

Now that Li Ming is retired, she likes to work in her garden—even in hot weather. Then last summer, an unusual heat wave hit her area. The temperature was over 100°F, and the humidity was at least 90%. By the third day, her daughter Kim came over because Li Ming sounded confused on the phone. Kim found her mom passed out on the kitchen floor. Li Ming's large fan wasn't enough to fight the effect of heat and humidity. She had heat stroke, the most serious form of hyperthermia.

Almost every summer, there is a deadly heat wave in some part of the country. Too much heat is not safe for anyone. It is even riskier if you are older or if you have health problems. It is important to get relief from the heat quickly. If not, you might begin to feel confused or faint. Your heart could become stressed and maybe stop beating.

Your body is always working to keep a balance between how much heat it makes and how much it loses. Too much heat causes sweating. When the sweat dries from your skin, the surface of your body cools, and your temperature goes down.

But being hot for too long can be a problem. It can cause several illnesses, all grouped under the name hyperthermia (hy-per-ther-mee-uh).

  • Heat syncope is a sudden dizziness that may happen when you are active during hot weather. If you take a kind of heart medication called a beta blocker or are unused to hot weather, you are even more likely to feel faint. Drinking water, putting your legs up, and resting in a cool place should make the dizzy feeling go away.
  • Heat cramps are the painful tightening of muscles in your stomach, arms, or legs. Cramps can result from hard work or exercise. While your body temperature and pulse usually stay normal during heat cramps, your skin may feel moist and cool.

    These cramps are a sign that you are too hot. Find a way to cool your body down. Rest in the shade or in a cool building. Be sure to drink plenty of fluids, but not those with alcohol or caffeine (coffee, tea, and some sodas). Caffeine can cause you to be dehydrated.
  • Heat edema is a swelling in your ankles and feet when you get hot. Putting your legs up should help. If that doesn't work fairly quickly, check with your doctor.
  • Heat exhaustion is a warning that your body can no longer keep itself cool. You might feel thirsty, dizzy, weak, uncoordinated, and nauseated. You may sweat a lot. Even though your body temperature stays normal, your skin feels cold and clammy. Some people with heat exhaustion have a rapid pulse. Rest in a cool place and get plenty of fluids. If you don't feel better soon, get medical care. Be careful—heat exhaustion can progress to heat stroke.
  • Heat stroke can be life threatening! You need to get medical help right away. Older people living in homes or apartments without air conditioning or fans are at most risk. So are people who become dehydrated or those with chronic diseases or alcoholism.

Signs Of Heat Stroke—A Medical Emergency

  • Fainting, possibly the first sign
  • Body temperature over 104°F
  • A change in behavior—confusion, being grouchy, acting strangely, or staggering
  • Dry flushed skin and a strong rapid pulse or a slow weak pulse
  • Not sweating even if it is hot, acting agitated, or being in a coma

Who Is At Risk?

Most people who die from hyperthermia each year are over 50 years old. Health problems that put you at greater risk include:

  • Heart or blood vessel problems, poorly working sweat glands, or changes in your skin caused by normal aging.
  • Heart, lung, or kidney disease, as well as any illness that makes you feel weak all over or results in a fever.
  • Conditions treated by drugs such as diuretics, sedatives, tranquilizers, and some heart and high blood pressure medicines. These may make it harder for your body to cool itself by sweating.
  • Taking several prescription drugs. Keep taking your medicine, but ask your doctor what to do if the drugs you take make you more likely to become overheated.
  • Being very overweight or underweight.
  • Drinking alcoholic beverages.

How Can I Lower My Risk?

Things you can do to lower your risk of heat-related illness:

  • Drink plenty of liquids—water, fruit, or vegetable juices. Aim for eight glasses every day. Heat tends to make you lose fluids, so it is very important to remember to keep drinking liquids when it's hot. Try to stay away from drinks containing alcohol or caffeine. If your doctor has told you to limit your liquids, ask what you should do when it is very hot.
  • If you live in a home or apartment without fans or air conditioning, try to keep your house as cool as possible.
  • Limit your use of the oven. Cover windows with shades, blinds, or curtains during the hottest part of the day. Open your windows at night.
  • If your house is hot, try to spend at least 2 hours during mid-day some place that has air conditioning—for example, go to the shopping mall, movies, library, senior center, or a friend's house.
  • If you need help getting to a cool place, ask a friend or relative. Some Area Agencies on Aging, religious groups, or senior centers provide this service. If necessary, take a taxi or call for senior transportation. Don't stand outside in the heat waiting for a bus.
  • If you have an air conditioner but can't afford the electric bills, there may be some local resources that can help. The Low Income Home Energy Assistance Program is one possible resource.
  • Dress for the weather. Some people find natural fabrics such as cotton to be cooler than synthetic fibers. Light-colored clothes feel cooler. Don't try to exercise or do a lot of activities when it's hot.
  • Avoid crowded places when it's hot outside. Plan trips during non-rush hour times.

Listen To Weather Reports

If the temperature or humidity is going up or an air pollution alert is in effect, you are at an increased risk for a heat-related illness. Play it safe by checking the weather report before going outside.

What Should I Remember?

Headache, confusion, dizziness, or nausea could be a sign of a heat-related illness. Go to the doctor or an emergency room to find out if you need treatment.

Older people can have a tough time dealing with heat and humidity. The temperature inside or outside does not have to reach 100°F to put them at risk for a heat-related illness.

To keep heat-related illnesses from becoming a dangerous heat stroke, remember to:

  • Get out of the sun and into a cool place—air-conditioning is best.
  • Drink fluids, but avoid alcohol and caffeine. Water, fruit, or vegetable juices are good choices.
  • Shower, bathe, or at least sponge off with cool water.
  • Lie down and rest in a cool place.
  • Visit your doctor or an emergency room if you don't cool down quickly.

A Senior Watch

During hot weather, think about making daily visits to older relatives and neighbors. Remind them to drink lots of water or juice. If there is a heat wave, offer to help them go some place cool, such as air-conditioned malls, libraries, or senior centers.

For More Information

Here are some helpful resources:

National Association of Area Agencies on Aging
1730 Rhode Island Avenue, NW
Suite 1200
Washington, DC 20036
1-202-872-0888
www.n4a.org

Eldercare Locator
1-800-677-1116 (toll-free)
www.eldercare.gov

Low Income Home Energy Assistance Program
National Energy Assistance Referral Hotline (NEAR)
1-866-674-6327 (toll-free)
www.acf.hhs.gov/programs/ocs/liheap

For more information on health and aging, contact:

National Institute on Aging Information Center
P.O. Box 8057
Gaithersburg, MD 20898-8057
1-800-222-2225 (toll-free)
1-800-222-4225 (toll-free/TTY)
www.nia.nih.gov
www.nia.nih.gov/espanol

To sign up for regular email alerts about new publications and other information from the NIA, go to www.nia.nih.gov/health.

Visit NIHSeniorHealth (www.nihseniorhealth.gov), a senior-friendly website from the National Institute on Aging and the National Library of Medicine. This website has health information for older adults. Special features make it simple to use. For example, you can click a button to have the text read out loud or to make the type larger.

National Institute on Aging
National Institutes of Health
U.S. Department of Health and Human Services

July 2010

Publication Date: July 2010
Page Last Updated: August 19, 2014