Heat Stroke

  • Medical Author:
    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.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    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.

Slideshow: Adult Skin Problems
Avoid Heat Emergencies, Keep Hydrated

How to Recognize a Heat Related Illness

The following checklist can help you recognize the symptoms of heat-related illnesses:

  1. Heat rash: Heat rash looks like a red cluster of pimples or small blisters.
  1. Heat cramps: A person with heat cramps may develop painful muscle spasms in the arms, legs, or abdomen referred to as heat rash. The body temperature is usually normal, and the skin will feel moist and cool, but sweaty.

Quick GuideDehydration: Causes, Symptoms and Tips to Stay Hydrated

Dehydration: Causes, Symptoms and Tips to Stay Hydrated

Heat stroke facts

  • Heat stroke is a form of hyperthermia in which the body temperature is elevated dramatically.
  • Heat stroke is a medical emergency and can be fatal if not promptly and properly treated.
  • The cause of heat stroke is an elevation in body temperature, often accompanied by dehydration.
  • Symptoms of heat stroke can include
  • Heat stroke is diagnosed by observation of the symptoms and signs in a person exposed to extreme temperatures.
  • Heat stroke is treated by cooling the victim is a critical step in the treatment of heat stroke. Always notify emergency services immediately if heat stroke is suspected.
  • The most important measures to prevent heat strokes are to avoid becoming dehydrated and to avoid vigorous physical activities in hot and humid weather.
  • Infants, the elderly, athletes, and outdoor workers are the groups at greatest risk for heat stroke.
  • Leaving infants, children, or animals in cars poses a risk for heat stroke. Even in moderate weather, the temperature inside a closed car can reach dangerous levels.

What is, and who is at risk for heat stroke?

Heat stroke is a form of hyperthermia or heat-related illness, an abnormally elevated body temperature with accompanying physical symptoms including changes in the nervous system function. Unlike heat cramps and heat exhaustion, two other forms of hyperthermia that are less severe, heat stroke is a true medical emergency that is often fatal if not properly and promptly treated. Heat stroke is also sometimes referred to as heatstroke or sun stroke. Severe hyperthermia is defined as a body temperature of 104 F (40 C) or higher.

The body normally generates heat as a result of metabolism, and is usually able to dissipate the heat by radiation of heat through the skin or by evaporation of sweat. However, in extreme heat, high humidity, or vigorous physical exertion under the sun, the body may not be able to sufficiently dissipate the heat and the body temperature rises, sometimes up to 106 F (41.1 C) or higher. Another cause of heat stroke is dehydration. A dehydrated person may not be able to sweat fast enough to dissipate heat, which causes the body temperature to rise.

Heat stroke is not the same as a stroke. "Stroke" is the general term used to describe decreased oxygen flow to an area of the brain.

Those most susceptible (at risk) individuals to heat stroke include:

  • Infants
  • The elderly (often with associated heart diseases, lung diseases, kidney diseases, or who are taking medications that make them vulnerable to dehydration and heat strokes)
  • Athletes
  • Individuals who work outside and physically exert themselves under the sun
  • Infants, children, or pets left in cars.

Heat stroke is sometimes classified as exertional heat stroke (EHS, which is due to overexertion in hot weather) or non-exertional heat stroke (NEHS, which occurs in climactic extremes and affects the elderly, infants, and chronically ill.

Medically Reviewed by a Doctor on 6/29/2015

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