Heat illness

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 30, 2016
StartDiseasesHeat illness

Heat illness represents a group of heat-related ailments. In all cases, extreme heat is recognized to be the underlying cause. However, symptoms of each specific heat illness can vary. As the Earth's climate continues to change, some individuals are experiencing hotter climates than anything they have previously been accustomed to. In addition, as the general population ages, there are increasing amounts of elderly people: a population that is vulnerable to heat illness. Heat illness is also called heat-related illness.


Definition & Facts

It is estimated that 68 percent of cases of heat illness in the United States are among males. On average, just over 600 deaths annually are attributed to heat illness according to the Centers for Disease Control and Prevention. In extremely hot years (such as 2006), the death toll from heat illness tends to rise.

Heat can be either the primary or a secondary cause of death. One ongoing issue with statistically tracking deaths linked to heat illness is that the death certificate does not always reflect "heat illness" as a cause. There are a number of different illnesses linked to heat illness. The most common of these include the following:

Heat stroke and heat exhaustion are both considered emergency situations for which medical attention should be sought immediately. Deaths have occurred due to delays in seeking treatment. Heat cramps or heat rash can precede heat stroke or heat exhaustion if medical attention is not promptly received.

Symptoms & Complaints

Symptoms vary based on the exact type of heat illness being experienced, and heat illnesses can arise suddenly without symptoms that could be used as an early warning system. Nevertheless, commonly reported symptoms of the various heat illnesses include the following:

Heat stroke:

Heat exhaustion:

Heat cramps:

Heat rash:

Other commonly reported general symptoms of heat illness include the following:


Heat illness is caused by the body's inability to regulate its temperature due to exposure to extreme heat. Whereas ordinarily, the body cools itself through sweating and maintains a normal body temperature of about 98.6 degrees Fahrenheit (37 degrees Celsius), during heat illnesses, the body is unable to cool itself quickly enough, and the body temperature rises dangerously. Increased body heat or hyperthermia can damage internal organs and cause death.

Diagnosis & Tests

Diagnosing heat illness begins with identifying which type of heat illness the individual is most likely suffering from. This can be done by taking a list of symptoms. Often, this is enough to make a diagnosis. If more information is required, a variety of tests may be ordered to confirm the specific diagnosis including the following:

  • Blood tests. To check for sodium and potassium levels in the blood.
  • Clinical urine tests. To check the color of the urine, whether blood is present, and kidney function.
  • Taking the individual's temperature. To check for elevated temperature.
  • Muscle function testing. To look for muscle damage.
  • X-rays & imaging tests. To look for damage to internal organs. Brain damage is sometimes a complication of heat illness and MRIs and CT scans can help detect this.

Treatment & Therapy

The treatment for heat illness will also depend in part on the type of heat illness and the severity of heat illness symptoms. General treatments commonly prescribed to treat heat illness include:

  • Stretching slowly or doing a gentle massage to ease cramping or aching muscles.
  • Relocation to a cool, sheltered area.
  • Loosening clothing.
  • Elevating the legs.
  • Applying cool compresses or ice packs to key areas (armpits, groin, neck, back) while the individual is wrapped in a medical cooling blanket.
  • Cool water mist on the skin with warm air fan overhead to evaporate the mist and cool the skin.
  • Immersion in cold water or ice water bath.
  • Taking a muscle relaxant to stop shivering (which otherwise raises body temperature and impedes treatment success).
  • Sipping water and/or electrolyte fluid to aid in rehydration (for heat exhaustion, heat cramps and heat rash only).

It is critical here to note that, for heat stroke and severe heat exhaustion in particular, medical intervention is necessary. It is not sufficient to attempt to treat these serious and potentially fatal conditions from home. Mild heat illness may be treated at home, but if home remedies do not work, medical attention should be sought promptly.

Prevention & Prophylaxis

Preventing heat illness of any kind is possible with some knowledge and planning. It is important to know who is most vulnerable (the young, the elderly, serious athletes, those with chronic medical conditions) and to take precautions accordingly. According to the CDC, air-conditioning is the most important preventative factor in warding off heat illness.

Staying out of the heat in the hottest parts of the day is an important prevention tactic. When going outside in hot weather, choose cool, light, loose-fitting clothing. Use sunscreen to protect skin from the effects of the heat, and wear a hat to protect the head.

Drink fluids (water, electrolyte drinks) to stay hydrated. Do not drink caffeinated or alcoholic beverages, which can cause dehydration. One should not wait until one is thirsty to drink. It is important to stay ahead of thirst. Also be aware of any medications that may raise sensitivity to heat

Never sit in a hot car for a long period of time or leave anyone else (a person or a pet) in a hot car for any length of time. Also stay attuned to the weather predictions and be prepared if an unusually hot period of weather has been predicted. Following these tips can prevent heat illness.