Heat Illness

What is Heat Illness?

Athletes who train and compete in warm climates should recognize that heat illness is a cause for concern and precaution. This spectrum of disorders can range from mild forms (heat edema, rash, or cramps), progressing to more serious disease (heat exhaustion), and ending with the life-threatening heat stroke. Fortunately, heat illness is completely preventable. Recognizing the signs and symptoms and initiating treatment for heat illness is essential, but it is even more important to understand the risk factors and implement strategies to prevent any problems.

Forms of Heat Illness

Heat edema is a mild form of heat illness that is noted by swelling of the body, usually the lower extremities. It usually occurs in individuals who have not adjusted to a warmer climate. Most often it is older individuals who move to a warmer location. Heat rash usually appears as a pinpoint rash that often itches significantly. It is most often seen in areas that are covered with clothing, such as the trunk or groin. Heat cramps occur when the athlete sweats heavily. The loss of fluids and electrolytes, especially sodium, causes painful muscle contractions and spasms. Heat exhaustion is a more serious form of heat illness characterized by profuse sweating, dizziness, headaches, nausea, vomiting, and fainting. Heat stroke occurs when heat exhaustion goes untreated, and the athlete starts to exhibit mental status changes, such as confusion, loss of balance, and irritability. Immediate recognition and treatment are crucial to prevent potentially fatal outcomes. 

Risk Factors

Many factors increase the risk of heat illness in athletes, even healthy ones. Dehydration is a critical factor — either from lack of sufficient fluid intake or excessive fluid loss through sweating. Certain populations, including the elderly and children, are thought to be at higher risk. Some medical conditions, such as obesity, recent fever, and sickle cell trait, can predispose individuals to heat illness. Numerous medications, including antihistamines, antidepressants, antipsychotics, stimulants, diuretics, and blood pressure medicines can increase the risk of heat illness. Important environmental risk factors include temperature, level of humidity, and type of clothing.


All forms of treatment for the various types of heat illness focus on reducing core body temperature. In milder forms, such as exertional heat illness, taking an athlete off the field and sitting him or her on the bench might be sufficient. Moving to a shaded area or inside an air-conditioned building is ideal if possible. Rest, elevation, and use of compressive stockings can reduce swelling from heat edema. If a heat rash is present, removing some of the clothing covering the area and using an anti-inflammatory cream is appropriate. If the athlete feels faint, lying on his or her back with the legs elevated can help return blood to the brain and resolve the condition. Rest, gentle stretching and massage of the muscles, and cooling with ice can relieve heat cramps. In all of these milder types of heat illness, replacement of fluids and electrolytes orally is critical. If the symptoms are severe, IV fluids might be indicated. 

More severe forms of heat illness require more aggressive treatments. If the athlete has symptoms of heat exhaustion, such as nausea, vomiting, or dizziness, his or her temperature needs to be checked. Cold sports drinks might be enough to reduce body temperature. If the temperature continues to remain elevated or the symptoms are severe, ice bags in the armpits and groin can help. Heat stroke requires rapid and emergent treatment. Ice baths or spraying cold water on the body and using fans to help evaporate the heat are critical, but transportation to an emergency facility is crucial.


Recognizing the signs and symptoms of heat illness is necessary for adequate treatment, but understanding the risk factors is vital to prevent a problem in the first place. Adequate hydration is essential. Fluids should be readily available — especially those with electrolytes, such as sports drinks. Supplements with stimulants to enhance performance should be strongly discouraged. Athletes must adjust to warmer climates gradually and maintain appropriate fitness levels for their sports. Maintenance of healthy body weight should be emphasized. Athletes with medical conditions such as a recent illness with a fever should be closely watched if allowed to play at all. Wearing light-colored clothes that are loose fitting and allow sweat to evaporate heat is beneficial. Taking frequent breaks and resting in cool locations should be encouraged. Restricting practice and competition when the temperature and humidity make the risk of heat illness significant is critical. Efforts to prevent heat illness in all athletes not only decreases risk of injury and illness but also can enhance performance.