Heat Exhaustion

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Slideshow: Understand the Risks and Signs of Dehydration

Who is at risk for heat exhaustion?

Heat exhaustion usually affects people who are working or exercising in a hot environment, and those who do not have access to adequate water. Those at risk for heat exhaustion include:

  • Infants and young children are at risk because their temperature regulation mechanisms are not fully developed. They also are dependent upon others for water and appropriate clothing.
  • The elderly are similarly at risk because of underlying medical conditions that limit the ability to sweat including poor circulation, skin changes, and chronic medication usage.
  • Socioeconomic issues increase the risk of heat exhaustion if access to air conditioning is limited. During heat waves, large cities often open cooling centers to help minimize the risk of large numbers of people succumbing to heat-related illness.
  • Certain medications such as antidepressants, antipsychotics, and tranquilizers may impair the ability of the body to sweat.
  • Alcohol consumption
  • The overweight or obese

The body has the ability to acclimate to hot weather but if heat waves come suddenly, or if a person travels from a cooler environment to a hot environment, the risk of heat exhaustion increases. It takes about 7 to 10 days for the body to adapt to hot weather. A non-acclimated person can produce a liter or almost a quart of sweat in an hour to assist in cooling the body. A person who is acclimated to the heat can produce 2 or 3 liters of sweat per hour, doubling or tripling the cooling potential for the body.

This water lost in sweat needs to be replaced for the sweating/cooling mechanism to work. A liter of sweat weighs 1 kilogram or 2.2 pounds.

When should an individual seek medical care for heat exhaustion?

Heat exhaustion usually can be treated at home as long as the affected individual can replace the lost fluid, keep well hydrated, and find a cool place to rest. Water, electrolyte replacement solutions or sport drinks are appropriate to consume. If nausea and vomiting prevent rehydration, the individual should seek medical attention, and may need IV fluids for rehydration.

Muscles cramps can be severe and if stretching and rehydration cannot relieve recurrent cramps, medical care also may be necessary.

It is important to recognize that if the person stops sweating, becomes confused, or has a seizure, heat stroke, a life-threatening condition, may be developing. Emergency medical services should be activated immediately (call 911 if available). The affected individual should be moved to a cooler place, have their clothing removed, and attempts should be made to cool the body with cold compresses, spraying or sponging the body with cool water and promoting air circulation with oscillating fans.

Medically Reviewed by a Doctor on 8/1/2016

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