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by Scholten A
Hyperthermia

Definition

Heat exhaustion is when the body overheats in hot temperatures. If not treated, it can lead to heat stroke. Heat stroke is more severe and can be life-threatening.

Causes

Heat exhaustion and heat stroke are caused when the body cannot cool itself. This can happen due to:

  • A very hot environment
  • Heavy activity
  • Too little fluid and salt intake

Risk Factors

Heat exhaustion is more common in young children and older adults.

Things that raise the risk of heat exhaustion and heat stroke are:

  • Being outside in hot weather for a long time
  • Little or no air conditioning
  • Problems with learning, behavior, or mental illness
  • Alcohol and street drugs
  • Certain medicines, such as:
    • Antipsychotics and lithium
    • Benzodiazepines and tricyclic antidepressants
    • Anticholinergics
    • Antihistamines
    • Beta-blockers
    • Certain blood thinners
    • Amphetamines
    • Thyroid agonists

Symptoms

Symptoms of heat exhaustion may be:

  • Temperature over 100 °F (degrees Fahrenheit) (37.8 °C [degrees Celsius])
  • Fast pulse
  • Moist skin, sweating
  • Muscle cramps or pain
  • Nausea and vomiting
  • Lightheadedness, confusion, or headaches

Symptoms of heat stroke may be:

  • Temperature over 105 °F (degrees Fahrenheit) (40.5 °C [degrees Celsius])
  • Weakness, lightheadedness
  • Blurred vision
  • Confusion, loss of consciousness, or seizures
  • Pale, dry skin with no sweating
  • Fast breathing or fast heartbeat

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done.

Blood and urine tests may be done to test body fluids.

Heart activity may be measured. This can be done with an ECG.

ECG Wave
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Treatment

Heat Exhaustion

Treatment for heat exhaustion includes:

  • Moving the person to a cool, shady area
  • Giving fluids—by mouth or IV
  • Rest

Heat Stroke

Treatment for heat stroke includes:

  • First aid, such as:
    • Removing clothing
    • Moving the person to a cool, shady area
    • Cooling the person— with cool water, cool spray mist, or fans
  • Hospital care, including:
    • Giving IV fluids
    • Giving medicines
    • Monitoring vital signs and organs

Prevention

To help reduce the risk of heat exhaustion and heat stroke:

  • Avoid being in high temperatures for long periods of time.
  • Drink lots of fluids (including sports drinks) and take rest breaks often.
  • During heat waves, stay in the shade, and indoors with air conditioning.

RESOURCES

American Red Cross  https://www.redcross.org 

Family Doctor—American Academy of Family Physicians  https://www.familydoctor.org 

CANADIAN RESOURCES

Canadian Red Cross  http://www.redcross.ca 

Health Canada  https://www.canada.ca 

References

Heat exhaustion and heatstroke. Family Doctor—American Academy of Family Physicians website. Available at: https://familydoctor.org/condition/heat-exhaustion-heatstroke. Accessed January 29, 2021.

Heat-related illnesses. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/heat-related-illnesses. Accessed January 29, 2021.

O'Connor FG. Sports Medicine: Exertional Heat Illness. FP Essent. 2019;482:15-19.

Revision Information

  • Reviewer: EBSCO Medical Review Board Shawna Grubb, RN
  • Review Date: 09/2020
  • Update Date: 03/01/2021