Heat Illness

ExitCare ImageIf the body is unable maintain a proper body temperature in hot and/or humid conditions during physical activity, severe illness may occur. To maintain a relatively constant body temperature, the body radiates heat out to the environment and evaporates sweat. In very hot and/or humid conditions, these two methods of heat loss may not work properly. In order to perform physically in such a climate, the body must have time to acclimate (make physiological changes to compensate), such as increase the rate of sweating. When performing physical activity in hot and/or humid environments, it is important to stay hydrated. Adequate hydration will help the body sweat properly. If the body temperature is allowed to increase too much, a person's judgment and performance will decline.


  • Dizziness.

  • Fatigue.

  • Changes in judgment.

  • Muscle cramps.

  • Weakness.

  • Nausea and vomiting.

  • Rapid heart rate.

  • Fainting.

  • Death.

  • Diarrhea.

  • Seizures.

  • Liver failure.

  • Kidney failure.

  • Low blood pressure.

  • Loss of consciousness (coma).

  • Elevated body temperature.


  • Hot and/or humid conditions.

  • Poor conditioning.

  • Not being acclimated to the heat.

  • Dehydration.

  • Obesity.

  • Inappropriate clothing (does not allow water to evaporate).

  • Age (very old and very young people).

  • Medications: diuretics, caffeine, decongestants, stimulants, some blood pressure medications.


  • Older age (decreased body water, decreased blood supply to skin, resulting in decreased sweating, decreased sweat rate).

  • Young boys (decreased sweat rate compared with men).

  • Dehydration.

  • Not being acclimated to the heat (this takes 1 to 2 hours per day for a minimum of 6 days).

  • Waiting until thirsty to drink.

  • Use of stimulants. Amphetamines, cocaine, or decongestants increase risk for heat illness.

  • Use of diuretics (increases urination).

  • Use of medicines with anticholinergic properties.

  • Use of medicines that slow the heart rate.


  • Maintain needed hydration before, during, and after exercise.

  • Wear clothing that allows sweat to evaporate (light colored, lightweight, breathable).

  • Take the time to acclimate to the heat.

  • Avoid salt tablets (they irritate the stomach).

  • Monitor weight after practices.

  • Avoid physical activity during the hottest times of day.


Most athletes who suffer from heat illness will recover completely, if treated. Severe heat illness is a medical emergency and may require hospitalization.


  • Rhabdomyolysis (death of muscle, resulting in weakness and pain).

  • Acute respiratory distress syndrome (lining of the lung is altered to prevent oxygen from getting into the bloodstream, which can result in death).

  • Disseminated intravascular coagulation (spontaneous clotting of the blood, resulting in an inability to make normal blood clots when needed).

  • Kidney failure.

  • Liver failure.

  • Seizures (abnormal electrical activity in the brain).

  • Death.


The most important treatment is to remove affected persons from the heat. Give the patient cool water to drink. For severe cases of heat illness, it may be necessary to cool the patient more aggressively, such as with an ice bath or cold shower. If symptoms persist after treatment, seek medical attention.


  • Oxygen is used in severe cases, if there is lung damage.

  • Fluid injections may be given for hydration.


  • A patient may return to sport as soon as he or she is able.

  • Heat illness may make an athlete vulnerable to future episodes of heat illness.

  • Allow the body to acclimate before performing in hot and/or humid conditions.


Drink 8 oz. of fluid before exercise and 4 oz. of fluid every 15 to 20 minutes during exercise.

As an alternative, try to drink about 1 quart of fluid for every hour of exercise.


  • You develop vomiting or diarrhea after exercising in the heat.

  • Someone collapses while exercising in the heat.

  • You have increasing problems exercising in the heat.

  • You notice increased muscle aches after exercising in the heat.

  • There is a change in the color of your urine after exercise.