Heat Exhaustion, First Aid

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Heat exhaustion is the moderate form of heat illness. Heat illness occurs when a person's core body temperature rises above a safe level of the body's internal temperature range. Heat cramps are the earliest sign of heat illness. If precautions to cool off and rehydrate at this point are not made, the more severe stage of heat illness, heat exhaustion, can occur in a rapid progression. The progression from the early stage of heat illness to heat exhaustion and subsequently to heatstroke can be very quick and can result in a potentially life-threatening situation.

See the Heat Cramps or Heatstroke texts via the Disease List for information specific to the other stages of heat illness.

First Aid Guide
Use a combination of the following measures depending on the circumstances and means available:

  • Have the person rest, legs slightly elevated, in a shaded area or cool or air-conditioned building, room, or car.
  • Remove or loosen the person's clothes.
  • Give the person an electrolyte drink, such as Gatorade® or Pedialyte®, or water if not available. Do not give beverages that contain caffeine or alcohol. Note: You can make a salted drink by adding 1 teaspoon of salt to one quart of water.
  • Pour water over the person or spray with a hose. Note: Do not do this if the person is disoriented.
  • Wrap the person in wet cloth, and position a fan toward him/her. Evaporation of water on the skin aids in cooling.
  • Apply cold compresses (eg, to neck, armpits, groin).
If possible, take the person's temperature while starting cooling measures and continue to check the temperature every few minutes. Once it has gone down to 100° F, you can discontinue cooling measures, but continue to check the person's temperature every 30 minutes for 34 hours to ensure it stays down.

Who's at risk?

People most susceptible to heat exhaustion are those who are outdoors on a hot, humid day or those inside in a poorly ventilated area, particularly children, the elderly, or the obese. Children and the elderly show the fastest progression of symptoms and can collapse suddenly.

Those on certain medications can suffer from heat illness, as well, as medications can alter the way the body handles heat and sun. Those who drink alcohol before, during, or after vigorous activity are more susceptible to heat illness, as are people who work or exercise excessively, coupled with profuse perspiration and inadequate fluid intake.

Even those in excellent health can have heat illness if early symptoms are ignored.

Signs and Symptoms

A person with heat exhaustion may feel faint or nauseated, be very thirsty, act irrationally, have dilated pupils (pupils are larger than normal), be very sweaty, or have cool and moist skin that is either reddened or pale.

You can differentiate the moderately severe form of heat illness, heat exhaustion, from more- or less-severe forms by comparing the person's symptoms described above to the following:

  • Heat cramps – Painful muscle cramps (eg, in the legs, arms, abdomen, or back), heavy perspiration, and general weakness/lightheadedness.
  • Heatstroke includes some or all of the following symptoms:
    • A high body temperature (above 102° F)
    • Skin that is red and hot with lack of sweating (sweating that has stopped)
    • Small pupils
    • A rapid, weak pulse
    • Rapid, shallow breathing
    • Extreme confusion or irritability
    • Weakness
    • Seizures
    • Unconsciousness

When to Seek Medical Care

If you suspect heatstroke, if there is no improvement with the above self-care measures after an hour, if symptoms worsen, or if there are signs of shock, seizure, or loss of consciousness, seek emergency medical care.

Treatments Your Physician May Prescribe

The physician will aim to cool the patient down in a controlled fashion, while ensuring he/she stays hydrated and has normal blood flow.

The physician will rehydrate the patient gradually by either giving an electrolyte drink or intravenous fluids.

Trusted Links

MedlinePlus: Heat Illness