Heat Stroke vs. Heat Exhaustion: Symptoms, Causes & Treatment

WRITTEN BY: Urgent Care
Friday, August 15th, 2014

This article was last updated June 14, 2016

While many sun worshippers count summer as their favorite time of year, the season comes with a host of health risks.

Matthew Synan, MD, of Pulmonary Consultants of UPMC, says heat-related conditions, such as heat stroke and heat exhaustion, are two common summertime ailments.

While these conditions are different, they’re often confused. Both conditions are on the spectrum of temperature-related illness, but they differ in severity.

Learn more about the negative effects of heat on the body.

What Causes Heat Exhaustion?

Heat exhaustion occurs when you’ve been exposed to extremely high temperatures and is often accompanied by dehydration. Specifically, a person experiences heat exhaustion when the body reaches a temperature of less than or equal to 104 degrees Fahrenheit.

There are two types of heat exhaustion. The first is water depletion, resulting in excessive thirst. The second is salt depletion, which can result in nausea and muscle cramps, among other symptoms.

Heat exhaustion symptoms and signs

  • Dizziness
  • Mild confusion (which normalizes within 30 minutes of treatment)
  • A faster heart rate with normal blood pressure
  • Mild to moderate dehydration.

What you should do if you believe you have heat exhaustion

  • Sit down and move to a cooler location
  • Drink water
  • Try applying a cool, wet cloths to your body
  • Spray water or fan yourself

What Is Heat Stroke?

Heat stroke occurs when the body reaches a core temperature of more than 105 degrees Fahrenheit. It is more serious than heat exhaustion.

Heat stroke is a medical emergency that can result in brain and/or internal organ damage. The condition occurs after prolonged dehydration and exposure to high temperatures. Heat stroke is often a progression from heat exhaustion, when the body’s mechanisms for controlling its temperature fail.

Heat stroke symptoms and signs

  • Abnormal mental status (such as delirium, hallucinations, or slurred speech),
  • A faster heart rate coupled with low blood pressure
  • Moderate to severe dehydration

What you should do if you believe you are experiencing heat stroke

  • Call 911 — heat stroke is a medical emergency
  • Move to a cooler location and remove unnecessary clothing
  • Spray water or fan to cool body temperature
  • Do not drink water

Types of Heat-Related Illness

There are two distinct types of heat stroke and heat exhaustion: classic and exertional.

  • Classic heat stroke and exhaustion can occur without any activity or physical exertion and is more common in individuals age 70 or older, or those who have a chronic medical condition.
  • Exertional heat stroke and exhaustion occurs as a result of physical activity and is most common in young individuals who engage in heavy exercise during high temperatures such as athletes and military recruits.

If not quickly treated, both these conditions may result in kidney failure, respiratory failure, liver failure, muscle breakdown, and even death.

Preventing Heat Stroke and Exhaustion

When the weather is hot, it’s important to take steps to prevent heat-related illness.

Limit physical activity in extreme temperatures, and head outside only in the evening, when it’s coolest. Wear loose clothing and take frequent breaks. Some medications, such as allergy, heart, or psychiatric prescriptions can put you at an increased risk, as these medications may limit the body’s ability to sweat.

“If any ‘woozy’ symptoms are felt — mainly due to low blood pressure as the capillaries are dilating to let the heat out — I advise my patients to lay down as soon as safely possible to help restore the most blood flow to the brain,” said Kevin Wong, MD, of West Moreland Family Medicine – UPMC.

You can also try lifting one leg, then the other, to increase blood flow to the heart and brain.

Dr. Wong said you’re more at risk of heat exhaustion if you take anything that dilates your blood vessels and drops your blood pressure, including medications or alcohol.

Visit to the Emergency Medicine at UPMC center for immediate treatment.


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