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.

Dehydration due to heat exhaustion

Signs and Symptoms of Heat Stroke

Sometimes a person may experience heat exhaustion before progressing to heat stroke. Heat stroke symptoms include:

  • Absence of sweating
  • Dry skin
  • Strange behavior
  • Agitation
  • Disorientation
  • Seizure

Heat stroke symptoms and signs also can mimic those of a heart attack or other conditions.

Heat exhaustion definition and facts

  • Heat exhaustion is one part of the spectrum of heat-related illnesses that begin with heat cramps, progresses to heat exhaustion, and finally to heat stroke.
  • The body cools itself by sweating and allowing that sweat to evaporate. This requires enough fluid in the body to make sweat, air circulating across the skin, and low enough air humidity to allow that sweat to evaporate.
  • Causes of heat exhaustion include activity in a hot environment that can overwhelm the body's ability to cool itself, causing heat-related symptoms, and living in a hot environment without adequate access to water for dehydration.
  • Signs and symptoms of heat exhaustion include
  • Heat exhaustion can progress to heat stroke when the body's temperature regulation fails. The person develops a change in mental status, becomes confused, lethargic and may have a seizure, the skin stops sweating, and the body temperature may exceed 106 F (41 C). This is a life-threatening condition and emergency medical attention is needed immediately.
  • First aid treatment for heat exhaustion includes recognizing the symptoms, stopping the activity, and moving to a cooler environment. Rehydration with water or a sports drink is the cornerstone of treatment for heat exhaustion.
  • Complications of heat exhaustion include nausea, vomiting, dehydration and muscle weakness. If the activity is not stopped and the person left in a hot environment, there can be progression of symptoms to heat stroke, a life threatening emergency.
  • Heat exhaustion can be prevented by being aware of your environment, especially on hot, humid days, and drink lots of fluids (no alcohol or caffeine).
  • Infants, children and the elderly are at risk because their bodies are less able to get rid of (dissipate) heat.
  • Infants and children are particularly at risk during hot weather. Never leave an infant, toddler, or child in the car when it is hot. An average of 38 children die each year after being trapped inside motor vehicles. When outside temperatures reach 80 F to 100 F (27 C to 38 C) the internal temperatures of vehicles parked in direct sunlight can reach up to 131 F to 172 F (55 C to 78 C). The inside of a vehicle with the windows rolled down two inches can reach 109 F (42.7 C) within 15 minutes.
  • Dogs and other pets also are at risk for heat exhaustion and heat stroke. They do not sweat through their skin and fur, but instead cool themselves by their foot pads, and panting and through their noses and mouths. Pet owners need to be aware of the environment and prevent prolonged exposure to heat, and provide adequate water to prevent dehydration. Never leave your pet in a vehicle when it is hot.
Medically Reviewed by a Doctor on 8/1/2016

Subscribe to MedicineNet's Skin Care & Conditions Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Health Solutions From Our Sponsors