Signs and Symptoms of Heat Illness

There are many heat-related illnesses, ranging from very treatable skin complaints to life threatening conditions. Any symptoms of heat illness indicates overexposure that may quickly worsen. Replacing fluids, taking frequent breaks and treating early symptoms is critical to avoid serious progression of the effects of heat.

Although heat illness can be cummulative, the most severe of these conditions– Heat Stroke– may occur without any warning

 The most common heat related illnesses are: 

Heat rash: Also called, “prickly heat,” or “Miliaria. The condition occurs when sweat glands become blocked and inflamed. Heat rash is most common in hot, humid environments where sweat accumulates on the surface of the skin for extended periods. The sweat ducts become plugged, and a painful or irritating rash emerges.

First Aid: Move the victim to a cooler, less, humid environment for the remainder of the work shift. The rash should be kept dry and clean to prevent infection. Talc based powder may be applied. Oily creams or ointments should not be used, as they may cause worsening of the rash. One of the best options is a mild drying lotion.  The worker should be examined for other signs of heat illness.  He must also maintain a well-hydrated state to prevent worsening illnesses. Cool showers and changing regularly into clean, dry clothes will help symptoms and prevent further incidents.

Heat syncope:  Lightheadness, dizziness or fainting (syncope) that typically occurs with prolonged standing (usually with knees straight and locked) or sudden rising from a sitting or lying position. Dehydration and lack of acclimatization (or adjustment to heat) often contribute to this condition.

First Aid: Workers with heat syncope should be removed from heat and made to rest in a cool place until the symptoms are relieved. Slowly sipping water to rehydrate should be encouraged. When recovered,the worker should move around and avoid static positions to prevent further syncope episodes.

Heat Cramps: Painful spasms of the involuntary muscles, generally in the extremities of arms and legs or abdomen. Low body salts and fluid loss, usually caused by heavy sweating, produce heat cramps. Heat cramps can occur with other heat-related illnesses, as well as individually. Body temperature is usually normal unless the cramps are accompanied by heat exhaustion. 

First Aid: Consume about 6-8 ounces of fluids such as water or electrolyte-replacement liquids, every 15 minutes. Do not take salt replacement tablets, unless directed by a physician. Strenuous work should be avoided for a few hours after the cramps subside, as further exertion can lead to worsening of symptoms or evolve into heat exhaustion or heat stroke. Stretching and massaging the muscles is beneficial. Drinking plenty of fluids prior and during heat exposure is necessary to prevent heat cramps.

If a worker is suffering heat cramps, the CDC advises professional medical attention if any of the following apply:

    • The worker has heart problems.
    • The worker is on a low-sodium diet.
    • The cramps do not subside within one hour.

Heat Exhaustion: Numerous factors cause heat exhaustion, including excessive sweat loss and dehydration which deplete the body’s fluid volume, as well as fatigue and overheat­ing. The victim may display any of several symptoms, including profuse sweating, nausea, or weakness.

The body temperature may exceed 100.4°F. This condition may also slowly develop over a period of days, as the victim gradually dehydrates while exposed to hot working environments.

Symptoms of heat exhaustion include:

  • Heavy sweating
  • Extreme weakness or fatigue
  • Dizziness, confusion
  • Nausea
  • Clammy, moist skin
  • Pale or flushed complexion
  • Muscle cramps
  • Slightly elevated body temperature
  • Fast and shallow breathing

 First Aid: Immediately remove the victim to a cool, shaded area. Remove as much clothing as possible. Provide non-caffeinated liquids, such as electrolyte replacement beverages or water to drink.  Apply cool water or cool wet compresses to the skin, particularly the face, back of neck, and under the armpits and groin.  The victim must be continuously monitored. Immediate return to work is not advised. OSHA requires these workers to have a medical evaluation. DO NOT let the victim drive themselves or leave them unattended. When at all possible, replacement of fluid using intravenous methods should be used.Call 911 immediately if the victim worsens.

 Heat Stroke: This is a very serious emergency that requires immediate medical attention. Heat stroke happens when the body’s temperature regulating and cooling mechanisms are not functioning effectively. Onset of heat stroke may be very rapid.The body temperature rises very high (106 °F or higher is not uncommon), while symptoms may include flushed skin, rapid breathing, racing heart rate, headache, and there may be a lack of sweating. However, in heat stroke that results from strenuous exercise, the skin may be moist and sweaty or may become clammy in later stages when shock may be present.

Muscles may cramp and/or may become limp or rigid. There may be neurological symptoms, such as loss of consciousness, odd behavior, hallucinations, and difficulty with comprehension or coma.  In fact, heat stroke is often characterized by mental confusion or other neurological symptoms.

According to the U.S. Fire Administration, “Any emergency personnel found in a hot environment with altered mental status and skin that is hot and dry, or moist to the touch, should be presumed to have a life-threatening heat-related emergency.”

Symptoms of heat stroke include:

  • Hot, dry skin or profuse sweating
  • Hallucinations
  • Chills
  • Throbbing headache
  • High body temperature
  • Confusion/dizziness
  • Slurred speech

 First Aid: This patient must be transported immediately by professional medical responders to a hospital emergency department. While waiting for emergency responders, aggressive cooling of the victim is necessary. Move the victim out of the sun or heat to a cool area. Remove as much clothing as possible.

Use cold water or wet rags on the victim’s skin.  Apply ice packs to the carotid arteries on the sides of the neck and under the armpits and groin, where large veins are located. Circulate air through fans on the victim if possible.  The quicker the body temperature is lowered, the more favorable the outcome. Aggressive cooling may reduce mortality rates from 50 percent to 5 five percent, according to some reports.

Do not give the victim anything to drink, as this may cause nausea.  Talk to the victim and keep them calm.  If the worker loses consciousness, monitor respiration and pulse and be prepared to administer CPR or rescue breathing.

NOTE: Heat stroke can occur as a single incident without warning.  Watch workers closely for signs of this or any other heat related illness. Even if effective treatment is initiated and the patient survives the initial episode, severe relapses are possible for several days post-event.  Severe temperature regulation impairment (possibly for life) may result if the victim recovers.

Helpful Resources:

 Just a brief disclaimer: Nothing here on this site constitutes legal or medical advice. There are countless variables that affect the workplace and while I (or other safety professionals) can offer general information, you’ll need on site assistance from a credible expert to fill in the gaps.




2 thoughts on “Signs and Symptoms of Heat Illness

  1. Thermocouples says:

    The experiments in question began several years ago, when researchers at Roehampton University in London found that healthy young men could cover significantly more distance during a timed run on treadmills in a hot laboratory if they supplemented their workout gear with an ice-cold strap-on neck collar. The collar, lined with flexible artificial-ice packs, noticeably lowered the skin temperature on the men’s necks.


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