Heat-Related Injuries

Heat-related injuries, including heat cramps, heat exhaustion, and heat stroke, are problems that occur when the body's cooling system is overloaded


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Too Hot to Handle

Texas was in the grip of a severe heat wave in August just as students were heading back to school after summer break. The extreme heat forced schools around the state to take action. In Plano, for example, children were kept inside for recess on very hot days. In Irving, the football coach cut short afternoon practices and had the players take extra water breaks. In Arlington, some football scrimmages were canceled, and others were scheduled after 7:00 p.m.

School officials were trying to prevent heat-related injuries. These are health problems that occur when the body's cooling system is overloaded. The body normally cools itself by sweating. Under some conditions, though, this system can start to fail. In such cases, a person's body temperature may rise quickly. Very high body temperatures can damage the brain and other vital organs.

What Are Heat-Related Injuries?

There three types of heat-related injuries:

  • Heat cramps. These are painful muscle cramps, usually in the stomach, arms, or legs, that may occur during heavy activity. Heat cramps are the least serious type of heat-related injury. It can be dangerous to ignore them, however, since they are an early warning sign that the body is having trouble with heat.
  • Heat exhaustion. This is the body's response to losing too much water and salt in sweat. It often occurs in people who exercise heavily or work in a hot, humid place, which makes them sweat a lot. Elderly people and those with high blood pressure are also prone to heat exhaustion. As the body overheats, blood flow to the skin increases, which decreases blood flow to other organs and causes weakness, confusion, and can cause collapse. If heat exhaustion is not treated, the person may suffer heat stroke.
  • Heat stroke. This is the most serious type of heat-related injury. Heat stroke, also known as sun stroke, occurs when the body becomes unable to cool itself down. The body's temperature may rise to 106 degrees Farenheit or higher within minutes. If heat stroke is not treated quickly, it can lead to brain damage or death.

Who Is At Risk?

Several things affect the body's ability to cool itself during very hot weather. One of the main ways the body cools itself is by sweating. The evaporation of sweat from the skin cools the body. When humidity (the amount of moisture in the air) is high, the sweat does not evaporate from the skin. Other things that can limit the body's ability to control its temperature include old or very young age, being overweight, fever, heart disease, sunburn, alcohol or drug use, and dehydration (dee-hy-DRAY-shun), which is excessive loss of water from the body due to illness or not drinking enough liquids.

Some people have a high risk of heat-related injuries:

  • Babies and children under age four. Babies and young children are very sensitive to the effects of high temperatures. They become dehydrated very quickly because of their small size. They are also unable to help themselves if they start to get overheated.
  • People over age 65. An older person's body may not control its own temperature as well as a younger person's. Older people are also less likely to notice and respond to changes in temperature.
  • People who are overweight. An overweight person's body may tend to hold onto more body heat than a normal-weight person's does.
  • People who are ill or taking certain medicines. Any illness or medicine that leads to dehydration raises the risk of heat-related injuries.

What Are the Symptoms?

Heat Cramps

  • Painful muscle cramps, usually in the stomach, arms, or legs
  • Heavy sweating

Heat Exhaustion

  • Heavy sweating
  • Cold, clammy skin
  • Paleness
  • Tiredness
  • Weakness
  • Dizziness
  • Headache
  • Fainting
  • Muscle cramps
  • Nausea
  • Vomiting
  • Fast, weak pulse
  • Fast, shallow breathing

Heat Stroke

  • Very high body temperature (above 103 degrees Farenheit by mouth)
  • No sweating
  • Red, hot, dry skin
  • Dizziness
  • Headache
  • Confusion
  • Nausea
  • Vomiting
  • Fast, strong pulse
  • Unconsciousness

What Is the Treatment?

Heat Cramps

Heat cramps usually occur during heavy activity. It is best for the person to stop being active and sit quietly in a cool place and drink sips of water, clear juice, or a sports drink. To relieve the muscle cramps, firm pressure is placed on the muscles or the muscles are massaged gently. It is important for the person not to return to heavy exercise for a few hours after the cramps go away, because this might lead to heat exhaustion or heat stroke. A doctor should be called if the cramps do not go away within an hour.

Heat Exhaustion

Medical help should be called immediately if the symptoms are severe, or if the person has heart disease or high blood pressure. Otherwise, it is important for the person to cool off by being taken to a shaded area and fanned or, if possible, moved into an air-conditioned room; it is best for him or her to lie down and remove heavy clothing. Sips of water and applying cool, wet cloths on the skin are helpful. A cool shower or bath may also help.

Heat Stroke

Heat stroke is a serious medical emergency. Medical help should be sought right away. While waiting for help, the person can be cooled off by getting out of the sun, being fanned, or being moved into an air-conditioned room. It is important for the person to lie down and remove clothing. Applying cool, wet cloths, or putting the person in a cool bath or shower will help. If the humidity is low, another solution is to wrap the person in a cool, wet sheet. If the person is outside, spraying him or her with a garden hose can be effective. Taking the person's temperature regularly, and keeping up the cooling efforts until it drops to 101 to 102 degrees Farenheit is important. Sometimes the person's muscles may start to twitch wildly as a result of heat stroke. If this happens, the person should be kept from getting hurt. It is important not to put anything in the person's mouth, and do not give him or her anything to drink. If vomiting occurs, the airway is kept open by turning the person onto his or her side.

Having a Heat Wave!

A heat wave is a long period of very high heat and humidity. The National Weather Service has come up with a heat index (HI)to warn the public about such conditions. The HI, given in degrees Fahrenheit, is a measure of how hot it really feels when the actual air temperature is combined with the relative humidity (which is a measure of the amount of moisture in the air compared to the greatest amount of moisture the air could hold at the same temperature). For example, if the air temperature is 95 degrees Farenheit and the relative humidity is 55 percent, the HI, or how hot it really feels, is 110 degrees F. The National Weather Service issues alerts when the HI is expected to be greater than 105 to 110 degrees Farenheit for at least two days in a row.

How Can Heat Injury Be Prevented?

To prevent heat-related injuries, keep cool and use common sense. The following tips may help on hot, summer days:

  • It is important to consume plenty of fluids, regardless of thirst. During heavy exercise in hot weather, it is important to drink at least two to four glasses of cool fluid each hour. Water is always a good drink choice. Very cold drinks can cause stomach cramps. Avoiding drinks containing caffeine, such as iced teas and colas, is important because they just cause the body to lose more fluid. Salt tablets should be avoided.
  • Slowing down the pace is important also. It is important to cut back on heavy exercise, or to move it to the coolest time of day, usually very early in the morning.
  • Staying indoors if possible also can help. The best way to beat the heat is to stay in an air-conditioned room. An electric fan can make things more comfortable, too, but a fan alone may not be enough during a severe heat wave. If it is very hot at home, spending a few hours at an air-conditioned mall or public library can help.
  • Lightweight, loose-fitting clothing also helps. Light-colored fabrics are the best, because they reflect away some of the sun's energy.
  • It is helpful to eat smaller, more frequent meals, to avoid generating the extra body heat associated with digesting large meals.

See also
Cold-Related Injuries


American Red Cross. "Are You Ready for a Heat Wave?" To order, contact the American Red Cross, 1621 N. Kent Street, 11 th Floor, Arlington, VA 22209, (703) 248-4222.

U.S. National Center for Environmental Health. "Extreme Heat: A Prevention Guide to Promote Your Personal Health and Safety." To order, contact the National Center for Environmental Health, Mail Stop F-29, 4770 Buford Highway N.E., Atlanta, GA 30341-3724.
Telephone 888-232-6789

U.S. Federal Emergency Management Agency (FEMA), 500 C Street S.W, Washington, DC 20472. A government agency that provides information about extreme heat.
Telephone 800-525-0321

U.S. National Weather Service, 1325 East-West Highway, Silver Spring, MD 20910. The government agency that issues alerts based on the heat index.
Telephone 301-713-4000

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