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Medical Author:

Steven Doerr, MD

Steven Doerr, MD

Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Heat-related illness facts
• What is a heat-related illness?
• What causes a heat-related illness?
• Who is at risk of heat-related illness?
• What are the symptoms of heat-related illness?
• Heat stroke
• Heat exhaustion
• Heat cramps
• Heat syncope
• Heat rash
• Heat-related illness prevention
• Find a local Doctor in your town
• Hyperthermia Index

Heat exhaustion is the body's response to an excessive loss of water and salt contained in sweat as a result of engaging in physical activity (work or exercising) in a hot environment. The body temperature may be normal or mildly elevated, but not above 104 F (40 C). It generally occurs in individuals who are not accustomed to working or exercising in the heat. The symptoms may range from minor complaints to more pronounced symptoms, however the affected individual will not experience the nervous system manifestations noted with heat stroke. Many cases of heat exhaustion can be treated outside of the hospital setting.

Warning signs of heat exhaustion include:

• a normal or mildly elevated body temperature,
• heavy sweating,
• pallor (paleness),
• muscle cramps and muscle pain,
• fatigue,
• weakness,
• dizziness and lightheadedness,
• headache, and
• nausea.

The skin may be cool and moist. The affected individual's pulse rate may be fast and weak, and breathing may be fast and shallow. If heat exhaustion is untreated and heat exposure continues, it may sometimes progress to heat stroke.

Cooling measures that may be effective include:

• drink cool, non-alcoholic beverages, such as water and sports drinks,
• eat salty snacks,
• rest in the shade or in an air-conditioned environment,
• take a cool shower or bath, and
• loosen or remove clothing.

Seek medical attention immediately if:

• the symptoms are severe, or
• the affected individual has serious underlying health problems (for example, heart disease or diabetes).

Otherwise, help the person cool off, and seek medical attention if symptoms worsen or last longer than one hour.