Heat Stress Education

Signs and Symptoms of Exertional Heat Stroke*

  • Weakness
  • Fatigue
  • Nausea
  • Dizziness/Light-Headedness
  • Altered consciousness
  • Collapse, staggering, or sluggish feeling
  • Fainting
  • Profuse sweating
  • Irritability
  • Diarrhea
  • Chills
  • Increase in core body temperature, usually above 104°F/40°C rectal temperature
  • Pale complexion
  • Decreased muscle coordination
  • Hot and wet or dry skin
  • Headache
  • Sodium Loss
  • Hyperventilation
  • Rapid Pulse, low blood pressure, quick breathing

* Adapted from Korey Stringer Institute: http://ksi.uconn.edu

Different Types of Heat Stress

Non-Exertional Heat Stroke

Non-exertional heat stroke is caused by just being in a hot environment, which leads to a rise in body temperature. Exertional heat stroke is caused by intense physical activity, which leads to an increase in body temperature. Working or exercising in hot or humid weather can lead to exertional heat stroke.

Exertional Heat Stroke

Exertional heat stroke is a medical emergency that could potentially lead to a life-threatened condition if not treated properly on-site. Exertional heat stroke occurs when the body temperature reaches above 105°F with central nervous dysfunction such as confusion, disorientation, seizures, or irrational behavior.

Non-Exertional vs. Exertional Heat Stroke

Non-exertional (or classic) heat stroke usually occurs in the elderly, infants, or patients with a congenital disease who may be at a disadvantage in regulating the body temperature from heat stress. Unlike exertional heat strokes, non-exertional heat strokes are prevalent in sedentary populations and may occur without strenuous physical activity.

Heat Exhaustion

Heat exhaustion occurs when your body cannot continue exercise due to heat stress. Often this is accompanied by dehydration. There are two kinds of heat exhaustion; water depletion and salt depletion. Signs of water depletion can include excessive thirst, weakness, headache, and loss of consciousness. For salt depletion, signs can include nausea and vomiting, muscle cramps, and dizziness.

Heat Syncope

Syncope is the medical term for fainting. Heat syncope is fainting due to overheating and occurs alongside a sudden change in posture or sudden stop in exercise. It occurs when water is evaporated from the blood, lowering the blood pressure further. Dehydration is a factor that contributes to heat syncope.

Heat Cramps

Heat cramps are muscle spasms that result from a large amount of salt and water loss during strenuous activity. Often they do not occur until after the activity, such as at night or when relaxing. Heavy sweating can cause heat cramps, particularly when water is replaced, but not salt or potassium.

Heat Rash

Heat rash is a skin irritation that can be caused by excessive sweat. A heat rash happens when sweat ducts become clogged, and the sweat cannot be released on the skin's surface. It becomes trapped beneath the skin’s surface, causing a rash or a mild inflammation. Heat rash can also be called prickly heat or miliaria.