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Topics > Healthy Outlook > Beware of Heat-Related Illnesses

Beware of Heat-Related Illnesses

Published by Contra Costa Times
Posted on Fri, July 06, 2007

By Dr. Stephen J. Daniels

HOT WEATHER is here and can cause hyperthermia or heat-related illness. Hyperthermia comes from prolonged exposure to a hot environment and/or strenuous exertion, combined with inadequate fluid intake.

Athletes can lose up to 11/2 quarts of liquid per hour through perspiration, and our bodies are capable of losing almost 3 quarts per hour under extreme conditions.

The elderly in environments without air-conditioning are particularly vulnerable during heat waves, as are infants and young children, the overweight and the chronically ill.

Many drugs, including some for the treatment of high blood pressure and depression, as well as some illegal drugs, can prevent the body from effectively lowering its temperature.

If you suspect heat-related illness, check the individual's temperature. However, the skin, mouth, ear or armpit temperatures can be normal even in the presence of serious hyperthermia deeper inside the body.

Heat-related illness is classified as heat exhaustion, which is relatively mild, or as heat stroke, which is a life-threatening condition.

Heat exhaustion becomes heat stroke when the body's temperature increases further, and causes internal damage.

Heat exhaustion

Heat exhaustion can develop after several days of exposure to high temperatures and inadequate or unbalanced fluid replacement. Strenuous exercise or physical exertion can cause heat exhaustion within a few hours.

Symptoms include:

  • Temperature of 98.6 degrees to 104 degrees
  • Heavy sweating
  • Muscle cramps and/or weakness
  • Dizziness and/or faintness
  • Headache, nausea and/or vomiting
  • The skin may be cool and moist, the pulse rate fast and weak, and breathing may be fast and shallow

Heat stroke

Heat stroke occurs when the body is unable to regulate its temperature. In heat stroke, the high temperature interferes with the body's central nervous system and other organ functions. Core body temperatures as high as 116 degrees have been recorded.

Symptoms include:

  • Temperature greater than 104 degrees
  • Red, hot, and dry skin (no sweating)
  • Rapid, strong pulse
  • Confusion, unconsciousness and seizures

If any of these symptoms occur, or if in doubt, call 911 immediately.


The fastest way to treat heat illness is a combination of cool mist sprayed on the skin, warm air fanning, and drinking a cooled rehydration liquid such as Gatorade.

The more skin exposed to the cool mist and fanned air the better. A completely unclothed person can lose up to one-half degree per minute using this method.

Fanning with cool air is less effective than with warm air because cool air can cause the blood vessels in the skin to constrict (become smaller), so less heat is lost to the surrounding air.

If mist and fanning are unavailable or undressing is inappropriate, use any method for cooling: a shady area or air-conditioned environment, a tub of cool water, a cool shower, spray from a cool garden hose, or a cool sponge bath.

Drinking water or other liquid is usually better than nothing, but drinking too much water can lead to internal salt imbalance. Do not give fluids if a person is unconscious or confused.

Call 911 if symptoms are severe, if you are unsure what to do, or if the victim has ongoing medical conditions.

For more information in both English and Spanish, visit the Contra Costa Health Services Web site at

Stephen Daniels practices family medicine at the Pittsburg and Concord Health Centers, part of the county Health Services Department.

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