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Core Knowledge


How to Beat Heat-Related Illnesses


As temperatures rise, the body uses its built in systems to cool itself. It does this by letting heat escape through the skin and by evaporating sweat. If your body does not cool properly, then you may suffer a heat stroke. Anyone can be affected by the heat, but older adults are especially vulnerable.

madmoiselle lavender / flickr

How it Happens

Heat-related illnesses occur when the body gets too hot. If you're exposed to high temperatures for a long time and don't replace lost fluids, the body systems that regulate temperature become overwhelmed. In the heat, your body cools when your sweat evaporates, but on hot days, the evaporation is slowed due to increased moisture in the air. As a result, your body produces more heat than it can control. Heat-related illnesses can also result when large volumes of sweat are replaced with fluids that don't contain enough salt.

By the Numbers

  • 400
    Number of people who die from heat-related illness each summer.
  • 47
    Percentage of heat-related illnesses that occur in adults older than 65.

Heat Cramps

Heat cramps typically occur during heavy exercise in extremely hot environments. As the body sweats, it is depleted of salt and moisture, which lowers salt levels in the muscles and can cause cramping. 

Symptoms of Heat Cramps

  • Hot, sweaty skin
  • Cramping in the calves, arms, legs, abdomen or back

Initial treatment

  • Rest and cool off
  • Drink clear juice or a sports drink
  • Gently stretch and massage muscles
  • If cramps don't subside in an hour, call your doctor

Heat Exhaustion

Heat exhaustion is the body's response to losing an excessive amount of water and salt. The body typically reacts by excessively sweating. Athletes, outdoor workers and elderly people are particularly susceptible to heat exhaustion. Heat exhaustion may occur after several days of exposure to extreme heat without proper fluids.

Symptoms of Heat Exhaustion

  • Difficulty continuing exercise, loss of coordination
  • Fatigue
  • Thirst
  • Rapid heartbeat
  • Pale or flushed complexion and clammy skin
  • Fainting, dizziness
  • Heavy sweating
  • Headache
  • Nausea, vomiting, diarrhea, cramps

Initial Treatment

  • Move the person to a cool, shaded or air-conditioned area
  • Have them lie down with their legs propped at heart level
  • Remove excessive clothes and equipment
  • Give the person cold water or a sports drink
  • Have the person take a cool shower
  • If they don't improve quickly, then take them to an emergency facility

Exertional Heat Stroke

The most serious of heat-related illnesses, exertional heat stroke occurs when the body can no longer control its temperature. If a person's body temperature rises above 103 degrees, they're suffering from heat stroke. Although treatable, exertional heat stroke can lead to heart attack, permanent disability or death.

Symptoms of Exertional Heat Stroke

  • Erratic behavior, slurred speech
  • Fainting, loss of consciousness
  • Confusion, dizziness, hallucinations
  • Abnormally high body temperature
  • Hot, sweaty skin
  • Chills
  • Headache

Initial Treatment

  • Call 911
  • Get the person to a cool, shaded area
  • Remove excess clothing and equipment
  • Douse person with cold water or soak in cold tub


  • Drink 16-32 ounces of cool fluids every hour 
  • Avoid alcoholic or sugary beverages 
  • Drink a sports beverage to replace the salt and minerals lost from sweating 
  • Wear lightweight, light-colored (they reflect the sun's energy), loose-fitting clothing 
  • Try to schedule outdoor activities for the coolest part of the day, which is usually between 4 a.m. and 7 a.m., or in the evening
  • Take regular rest breaks in shady areas 
  • Pace yourself. Start exercise sessions slowly and gradually pick up the pace. 

Jim Brown, Ph.D. has written 14 books on health, medicine, and sports. His articles have appeared in the Washington Post, New York Post, Sports Illustrated for Women and Better Homes & Gardens. He also writes for the Duke School of Medicine, UCLA School of Medicine, Cleveland Clinic and Steadman-Hawkins Research Foundation.

Tags: Hydration, Outdoor Recreation, Health


  1. American Red Cross
  2. Centers for Disease Control and Prevention
  3. Gatorade Sports Science Institute
  4. University of Maryland Medical Center
  5. American College of Sports Medicine
  6. Susan Yeargin, Ph.D., LAT, ATC