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.

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. Schools in Plano, for example, kept their children 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 pm.

School officials were trying to prevent heat-related injuries, which 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?

Heat-Related Injuries

Illustration by Electronic Illustrators Group. © 2016 Cengage Learning®.

Heat-related injuries are divided into three types:

Having a Heat Wave!

A heat wave is a long period of very high heat and humidity. The National Weather Service uses a heat index (HI) to indicate when people should be warned about such conditions. The HI, given in degrees Fahrenheit, is a measure of how hot it 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°F (35°C) and the relative humidity is 55 percent, the HI, or how hot it feels, is 110°F (43°C). The National Weather Service issues alerts when the HI is expected to be greater than 105°F (40°C) to 110°F (43°C) for at least two days in a row.

Who Is at Risk?

Several factors 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, sweat does not evaporate from the skin. Other factors that can limit the body's ability to control its temperature include fever, heart disease, sunburn, alcohol or drug use, and dehydration, which is excessive loss of water from the body due to illness or not drinking enough liquids.

People at high risk of heat-related injuries include:

What Are the Symptoms?

Heat cramps Heat exhaustion Heat stroke
When Heat Kills

An extreme heat wave settled on the city of Chicago in July 1995, bringing soaring high humidity paired with seven consecutive days of air temperatures of at least 90°F (32°C). On two of those days, the thermometer soared to 102°F (38°C) and 106°F (41°C). The 106°F mark was a record. On that day, the humidity was also very high and made the temperature feel like at least 120°F (48°C). For hundreds of residents, the extreme heat was fatal. Many of the victims were elderly individuals who either had no air conditioners in their homes or who were unable to afford the cost to run their air-conditioning systems. A power outage in parts of the city made the problem even worse. By the end of the heat wave, an estimated 500 to 700 local people had died from the heat.

What Is the Treatment?

Heat cramps

Heat cramps usually occur during heavy activity. Medical professionals advise a person experiencing heat cramps to stop his or her activity, sit quietly in a cool place, and sip water, clear juice, or a sports drink. Firm pressure on or a gentle massage of the muscles will help to relieve the muscle cramps. Even after the cramps have disappeared, the individual should avoid returning to heavy exercise for a few hours, because this level of activity might lead to heat exhaustion or heat stroke. An individual whose cramps have not gone away within an hour should call a doctor.

Heat exhaustion Heat stroke

Heat stroke is a serious medical emergency, and onlookers should summon medical help right away. While waiting for assistance, caregivers can help the person cool off by getting her or him out of the sun and fanning the patient or by moving the person into an air-conditioned room. There, the person should 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 the person lightly with a garden hose can be effective. Those providing first aid should take the person's temperature regularly and continue the cooling efforts until the person's temperature drops to 101°F to 102°F (38°C). Sometimes the person's muscles may start to twitch wildly as a result of heat stroke. If this happens, the caregiver's job is to keep the person from getting hurt. The caregiver should not, however, put anything in the person's mouth or give anything to the person to drink. If vomiting occurs, the caregiver should keep the airway open by turning the person onto his or her side.

How Can Heat Injury Be Prevented?

The best ways to prevent heat-related injuries are to keep cool and use common sense. The following tips may help on hot summer days:

See also Cold-Related Injuries • Fever • Fluid and Electrolyte Disorders


Books and Articles

Burke, Jason. “India Heatwave Kills More Than 500 People.” Guardian, May 25, 2015. https://www.theguardian.com/world/2015/may/25/india-heatwave-deaths-heatstroke-temperatures (accessed June 8, 2016).

Rubin, Bonnie Miller, and Jeremy Gorner. “Fatal Heat Wave 20 Years Ago Changed Chicago's Emergency Response.” Chicago Tribune, July 15, 2015. http://www.chicagotribune.com/news/ct-chicago-heat-wave-20-years-later-met-20150715-story.html (accessed July 16, 2015).


U.S. Environmental Protection Agency (EPA). “Climate Change Indicators in the United States: Heat-Related Deaths.” https://www3.epa.gov/climatechange/science/indicators/health-society/heat-deaths.html (accessed June 8, 2016).


American Red Cross National Headquarters. 2025 E St. NW, Washington, DC 20006. Toll-free: 800-RED CROSS (733-2767). Website: http://www.redcross.org (accessed July 16, 2015).

Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30333. Toll-free: 800-311-3435. Website: http://www.bt.cdc.gov (accessed July 16, 2015).

Federal Emergency Management Agency. 500 C St. SW, Washington, DC 20472. Toll-free: 800-621-FEMA. Website: http://www.fema.gov (accessed July 16, 2015).

National Weather Service, Office of Climate, Water, and Weather Services. 1325 East-West Highway, Silver Spring, MD 20910. Website: http://www.nws.noaa.gov/os (accessed June 8, 2016).

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)