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Heatstroke is a potentially life-threatening condition in which the body's ability to cool itself stops functioning correctly and body temperature rises to dangerous levels.


Heatstroke is the most dangerous of the heat-related illnesses. It is more serious than either heat cramps or heat exhaustion. Untreated heatstroke can cause death . Heatstroke occurs most frequently during heat waves and during very hot, humid weather. It can occur even without significant exertion, but instead just by exposure to very hot conditions. Heatstroke and other heat-related illnesses cause a serious public health concern during periods of very hot weather, and many cities open schools and other building to seniors and others at risk for heatstroke so that they can have cool, safe place to spend the hottest parts of the day.


Anyone can get heatstroke. However, seniors are more likely to be affected by heatstroke than younger

adults. Young children are also more likely to be affected. Seniors are more likely to be affected because their central nervous system is not as efficient at regulating temperature as it once was. Seniors who do not go out regularly or who are not able to care for themselves are even more likely to be affected by heatstroke.

Individuals taking certain medications are more likely to be affected because the medications can interfere with the body's normal cooling mechanisms. Individuals taking some blood pressure and heart medications, allergy medications, diet pills, water pills, cold medicines, medicines to prevent seizures, laxatives , and thyroid pills are at increased risk for heatstroke. Individuals who are overweight, and individuals who have cardiac conditions are also at increased risk.

Causes and symptoms

Heatstroke is caused by the body being unable to cool itself effectively. Normally, the body cools itself by sweating. The sweat dampens the surface of the skin and then evaporates, causing a cooling effect. When the body's ability to sweat is compromised, or the conditions are so hot that sweating is not producing enough of a cooling effect, the internal temperature of the body begins to rise and heatstroke can occur.

Heatstroke is caused by a significant raise in body temperature. An individual experiencing heatstroke typically has a body temperature above 104°F (40°C). The individual often has skin that is dry and warm, but in many cases is no longer sweating. If the individual was recently doing strenuous exercise the skin may still feel moist. The individual's heart rate increases, and he or she may begin to hyperventilate (rapid, shallow breathing). Headache, nausea, and fatigue may occur. The individual may appear to be confused, and may have difficulty understanding or responding to things that are said. Heatstroke can lead to dizziness , hallucinations, and even to seizures and coma .


A doctor or emergency medical technician can usually tell that an ideal is experience heatstroke from the symptoms displayed and a knowledge of the heat level where the individual was. The doctor may however do a variety of tests to determine the extent of the damage caused by the heatstroke and to determine what other treatments may be necessary. The doctor may do a urine test to check urine color and to test kidney function, a blood test to test potassium and sodium levels, a muscle test to determine if there has been damage to the muscles, and x-ray tests to determine the extent of organ damage.


The goal of heatstroke treatment is lowering the body's temperature and helping the body's natural cooling mechanisms to begin functioning again. When an individual seems to have the signs and symptoms of heatstroke medical attention should be sought immediately. While waiting for help to arrive the individual should be moved to an air-conditioned building or a place in the shade. The individual should be given cool, non-caffeinated, non-alcoholic, liquid if he or she is able to drink. The individual can be sprayed with cool water, or even submersed in a bathtub of cool water, to help bring down the body temperature. Fanning the individual to help circulate air over the damp skin can mimic the act of sweating and further reduce body temperature.

Heatstroke is a medical emergency. An individual experiencing heatstroke should be taken to the hospital as quickly as possible. There the emergency room staff will reduce the individual's body temperature in one ore more of a variety of ways. The individual may be placed in a bath of cool or ice water. The doctor may instead choose to place the individual under cooling blankets and put ice packs where the blood flows closest to the surface of the body such as the armpits, behind the neck, and the groin area. Another option for cooling the patient is spraying him or her with cool water and then using a fan to move warm air over the patient to simulate sweating.

Additional fluids and medications may be given intravenously during the treatment. Shivering is the body's natural response to cold conditions, and the patient being treated may begin to shiver. Because shivering is designed to warm up the body, it is counterproductive when an individual is being treated for heatstroke. In the patient begins to shiver during treatment the doctor may give him or her a muscle relaxant to stop the shivering and allow the cooling treatment to work.


  • Do any of my medications put me at increased risk for heatstroke?
  • Do any of my diseases or conditions put me at increased risk for heatstroke?
  • What are some strategies to ensure I can still participate in my favorite activities while not putting myself at risk of heatstroke?

Nutrition/Dietetic concerns

When an individual experiences heatstroke he or she is not getting enough fluids. Often the individual's electrolytes are depleted as well. Drinking fluids like water that do not contain caffeine , alcohol, or large amounts of sugar can help restore fluid levels and improve the body's ability to sweat. Drinking sports drinks, like Gatorade, can help to restore both fluids and electrolytes.


When heatstroke is found early and treated promptly no additional therapy is generally required. When permanent organ, muscle, or brain damage is caused by heatstroke physical or occupational therapy may be required.


Untreated heatstroke can be fatal. Even when not fatal it can lead to permanent damage to the organs, muscles, central nervous system, cardiovascular system, and brain. Heatstroke is, however, extremely treatable when the signs and symptoms are detected early. Individuals are more likely to die of heatstroke if they are not producing urine, are in a coma, or have heart failure when they arrive at the hospital. Treating heatstroke early can prevent these complications.


The key to preventing heatstroke is to avoid exertion during very hot days, to stay out of direct sunlight, and to drink plenty of fluids. Individuals should wear light, loose fitting clothing on hot days to help allow sweat to evaporate and cool the body efficiently. Individuals should drink two to four eight-ounce glasses of water every hour in extremely hot weather, even if they do not feel thirsty. On very hot days when people, especially seniors, feel thirsty it is a sign that there is already a problem. Individuals who are at increased risk of heatstroke should try to spend as much of the day as possible in air-conditioned buildings or in the shade. Senior centers, community centers, churches, and other organizations often open on hot days to allow individuals a place to stay out of the heat.


Hyperventilation —Rapid, shallow breathing.

Any signs of heat-related illness should be taken extremely seriously. Beginning treatment when heat cramps or heat exhaustion occur, before they progresses to heatstroke, can prevent heatstroke and dangerous complications. Individuals should avoid drinks that contain alcohol, large amounts of sugar, and caffeine on very hot days. These substances can actually inhibit the body's ability to cool itself, so drinking them may increase the severity of the heat related illness instead of treating it.

Caregiver concerns

It is extremely important to ensure that seniors drink enough fluids during very hot days. Fluids should be drunk regularly, even before the individual feels thirsty. This is especially important for seniors whose sense of thirst is often slightly impaired. Caregivers should make sure that the individual stays out of the sun, or if in the sun takes frequent rests in a cool area. It is also important to check on individuals who might be at risk for heatstroke, even those who do care for themselves, regularly on very hot days. If any of the sings of heatstroke are observed the caregiver should being cooling the individual immediately and call for medical assistance right away.



Armstrong, Lawrence, E., ed. Exertional Heat Illnesses. Champaign, IL: Human Kinetics, 2003.

Spengler, Daniel P., Andrew Connaughton, and Andrew T. Pittman. Risk Management in Sport and Recreation. Champaign, IL: Human Kinetics, 2006.


Argaud, Laurent, et al. “Short- and Long-Term Outcomes of Heatstroke Following the 2003 Heat Wave in Lyon, France.” Archives of Internal Medicine 167.20(November 12, 2007): 2177–2184.

Lewis, Anne Marie. “Heatstroke in Older Adults: In This Population It's a Short Step From Heat Exhaustion.” American Journal of Nursing 107.6 (June 2007): 52–57.

Moran, Daniel S., Tomer Erlich, and Yoram Epstein. “The Heat Tolerance Test: An Efficient Screening Tool for valuating Susceptibility to Heat.” Journal of Sport Rehabilitation 16.3 (August 2007): 215–221.

Helen Davidson


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heatstroke A dangerously high body temperature (hyperthermia) — above 41°C or 106 °F — which may be accompanied by coma or convulsions, and requires emergency life-saving measures. The body has passed the limit of its heat-losing mechanisms. It may follow from the less serious condition of heat exhaustion due to excessive sweating and dehydration during heat exposure, usually with heavy work or exercise in a hot environment.

Stuart Judge

See heat exposure; sweating.


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heat·stroke / ˈhētˌstrōk/ • n. a condition marked by fever and often by unconsciousness, caused by failure of the body's temperature-regulating mechanism when exposed to excessively high temperatures.


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heatstroke (sunstroke) (heet-strohk) n. raised body temperature (pyrexia), absence of sweating, and eventual loss of consciousness due to failure or exhaustion of the temperature-regulating mechanism of the body.


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heatstroke Condition in which the body temperature rises above 41°C (106°F). It is brought on by exposure to extreme heat. In mild cases there may be lassitude and fainting; in severe cases, collapse, coma and death may ensue.