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.

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Treatment

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.