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Heat emergencies

Heatstroke; Heat illness; Dehydration - heat emergency

Heat emergencies or illnesses are caused by exposure to extreme heat and sun. Heat illnesses can be prevented by being careful in hot, humid weather.

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Heat emergencies

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Causes

Heat injuries can occur due to high temperatures and humidity. You are more likely to feel the effects of heat sooner if:

The following make it harder for the body to regulate its temperature, and make a heat emergency more likely:

Symptoms

Muscle cramps are the first stage of heat illness. If heat exposure continues and these symptoms are not treated, they can lead to heat exhaustion and then heat stroke.

Heat stroke occurs when the body is no longer able to regulate its temperature, and it keeps rising. Heat stroke can cause shock, brain damage, organ failure, and even death.

The early symptoms of heat illness include:

Later symptoms of heat exhaustion include:

The symptoms of heatstroke include those of heat exhaustion in combination with very high body temperature and significant neurologic symptoms (call 911 or the local emergency number right away):

First Aid

If you think a person may have heat illness or emergency:

  1. Have the person lie down in a cool place. Raise the person's feet about 12 inches (30 centimeters).
  2. Apply cool, wet cloths (or cool water directly) to the person's skin and use a fan to lower body temperature. Place cold compresses on the person's neck, groin, and armpits.
  3. If alert, give the person a beverage to sip (such as a sports drink), or make a salted drink by adding a teaspoon (6 grams) of salt per quart (1 liter) of water. Give a half cup (120 milliliters) every 15 minutes. Cool water will do if salt beverages are not available.
  4. For muscle cramps, give beverages as noted above and massage affected muscles gently, but firmly, until they relax.
  5. If the person shows signs of shock (bluish lips and fingernails and decreased alertness), starts having seizures, or loses consciousness, call 911 or the local emergency number and give first aid as needed.

Do Not

Follow these precautions:

When to Contact a Medical Professional

Call 911 or the local emergency number if:

Prevention

The first step in preventing heat illnesses is thinking ahead.

To help prevent heat illnesses:

After recovering from exertional heat illness, check with your health care provider for advice before returning to heavy exertion. Begin exercise in a cool environment and slowly increase the degree of heat. Over several weeks, increase how long and how hard you exercise, as well as the amount of heat.

Related Information

Overweight
Dehydration
Shock

References

Landry GL. Heat Injuries. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 710.

O'Brien KK, Leon LR, Kenefick RW, O'Connor FG. Clinical management of heat-related illnesses. In: Auerbach PS, Cushing TA, Harris NS, eds. Auerbach's Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 13.

Platt M, Price MG. Heat illness. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 133.

Prendergast HM, Erickson TB. Procedures pertaining to hypothermia and hyperthermia. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 65.

Sawka MN, O'Connor FG. Disorders due to heat and cold. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 101.

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Review Date: 11/13/2021  

Reviewed By: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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