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Heat Stroke vs Heat Exhaustion

An older woman working in a garden in the sun, and looking exhausted

Heat-related illnesses are preventable. Learn the symptoms and what to do if you or a loved one shows signs of having a heat-related illness.

What happens to the body as a result of exposure to extreme heat?

People suffer heat-related illness when the body’s temperature control system is overloaded. The body normally cools itself by sweating. But under some conditions, sweating just isn’t enough. In such cases, a person’s body temperature rises rapidly. Very high body temperatures may damage the brain or other vital organs. Several factors affect the body’s ability to cool itself during extremely hot weather. When the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly. Other conditions that can limit the ability to regulate temperature include old age, youth (age 0-4), obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, and prescription drug use and alcohol use.

Who is at greatest risk for heat-related illness?

Those at greatest risk for heat-related illness include infants and children up to four years of age, people 65 years of age and older, people who are overweight, and people who are ill or on certain medications.

What is heat exhaustion?

Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. Those most prone to heat exhaustion are elderly people, those with high blood pressure, and those working or exercising in a hot environment.

Heat Exhaustion Symptoms

  • Heavy sweating
  • Cold, pale, and clammy skin
  • Fast, weak pulse
  • Muscle cramps
  • Tiredness or weakness
  • Fainting (passing out)
  • Nausea or vomiting
  • Dizziness
  • Headache

If You Are Experiencing Heat Exhaustion Symptoms

  • Move to a cool place
  • Loosen your clothes
  • Put cool, wet cloths on your body or take a cool bath
  • Sip water

What is heat stroke?

Heat stroke is the most serious heat-related illness. It occurs when the body becomes unable to control its temperature: the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not provided.

Heat Stroke Symptoms

  • High body temperature
  • Hot, red, dry or damp skin
  • Fast, strong pulse
  • Confusion
  • Losing consciousness
  • Nausea
  • Dizziness
  • Headache

 If You Are Experiencing Heat Stroke Symptoms

  • Call 911 immediately
  • Move the person to a cool place
  • Help lower the person’s body temperature with cool cloths or a cool bath
  • Do not give the person anything to drink

Tomah Health