Heat Stroke vs. Heat Exhaustion? How to Tell the Difference

As temperatures continue to rise across the US, it's crucial to know difference between heat stroke and heat exhaustion.

Mercey Livingston CNET Contributor
Mercey Livingston is a health and wellness writer and certified Integrative Nutrition Health Coach. She's written about fitness and wellness for Well+Good, Women's Health, Business Insider, and Prevention.com among others. When not writing, she enjoys reading and trying out workout classes all over New York City.
Mercey Livingston
4 min read
hand holding a thermostat

Summer means soaring temperatures, which can put you at risk for heat-related illness.

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The US is experiencing dangerous heat and humidity levels that could break temperature records. Extreme heat is more than just uncomfortable; it can be dangerous and even life-threatening. Heat is the leading cause of weather-related deaths in America.

So whether you're indoors without AC, or outside often for work or play, it's crucial to know the signs and symptoms of heat-related illnesses and what to do if it happens to you or someone you are with.

We spoke with Dr. Eric Adkins, emergency medicine physician at the Ohio State Wexner Medical Center, to dig into the difference between heat stroke and heat exhaustion, the signs and symptoms to look for and what you can do to prevent heat-related illness this summer.

Read more: Know the Signs of Heat stroke and What to Do Immediately If You Overheat

Heat stroke vs. heat exhaustion 

Heat-related illness can strike in several different conditions, according to Mayo Clinic. Heat stroke can occur if someone is exposed to hot, or hot and humid conditions for prolonged periods of time, long enough to raise someone's core body temperature to dangerous levels. Any weather conditions with a heat index of 91 degrees or higher is considered a risk factor for heat-related illness, and keep in mind that humidity only adds to the intensity. 

Heats troke can also be triggered while doing physical activity or labor in hot conditions. Factors like dehydration, alcohol consumption, and wearing lots of layers of clothing can make the condition come on faster or more likely to occur.

Symptoms of heat exhaustion usually strike before heat stroke, but heat exhaustion can result in a stroke if not treated soon enough. "The main difference between heat stroke and heat exhaustion involves the nervous system in heat stroke," Adkins says. "When having heat stroke, patients develop confusion and altered levels of consciousness. Other examples might be seizures, severe headache or irritability."  

Warning signs of heat stroke, according to the Centers for Disease Control and Prevention, include:

  • High body temperature (103 or higher)
  • Hot, red, dry or damp skin
  • Fast, strong pulse
  • Headache
  • Dizziness
  • Nausea
  • Confusion
  • Passing out or losing consciousness

If you think you or someone you are near is experiencing heat stroke, you should call 911 right away. While you wait for medical attention to arrive it's important that you try to help the person cool off by moving them inside or to a cooler area, or lower their body temperature with a cool bath or cool cloths. The CDC says it's important that you do not give someone who may be experiencing heat stroke anything to drink. That may sound counterintuitive, but you should wait for medical responders to arrive first. 

If you are unsure whether you or another person is experiencing heat stroke, it's best not to take any chances. "If there is any doubt, I recommend getting checked to be sure that their symptoms are not from heat exposure or some other potential emergency," Adkins says. 

Warning signs of heat exhaustion, according to the CDC:

  • Heavy sweating.
  • Cold, pale, clammy skin.
  • Fast, weak pulse.
  • Nausea or vomiting.
  • Muscle cramps.
  • Tiredness or weakness.
  • Dizziness.
  • Headache.
  • Passing out or fainting.

If someone is experiencing heat exhaustion, they should immediately try to cool down and apply cold cloths as needed or take a cool bath. They can drink small sips of water, but if the person is throwing up, they should call 911 or go to the hospital. You should also seek medical attention if the symptoms start to get worse, or lasts longer than one hour.

Young girl drinking water while playing outside

Children and the elderly are at risk for heat-related illness, so it's important to make sure they don't overheat and stay hydrated.

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How to prevent a heat stroke or heat exhaustion 

Heat-related illness is totally preventable, especially if you can avoid going outside for long periods during heat waves. "If you have to go outside, try to do it during times earlier or later in the day when the heat may be less severe," Adkins says. "Be sure to drink plenty of water if you don't have any restrictions on water intake from a medical condition, such as chronic heart failure."

For those who don't have AC at home or access to places with air conditioning, the situation is trickier. "If you don't have access to places with AC, try to use fans for air circulation and you can use cool towels to help the body with allowing heat to escape," Adkins says. "Water-soaked towels can help the body eliminate heat and work even better when combined with fans."

Who is most at risk?

Knowing who is most susceptible to heat stroke can help you identify it faster, and get help for someone who is in trouble. Anyone can experience heat stroke when exposed to high temperatures, even if they are indoors and without AC. "The elderly and young children that may not be able to recognize they are overheating or aren't able to communicate to someone they feel hot are at more risk," Adkins says. 

For this reason, it's important to watch children closely if they are playing outside in the heat, or if they are inside where there is no access to AC or fans. Don't forget that many elderly people are indoors now, and not all of them have AC. 

"I usually recommend that people try to check on older neighbors without AC during high-heat conditions," Adkins says. "It is still possible to stay socially distant and use masks to check on loved ones and neighbors."

Besides children and the elderly, other factors can put you more at risk for heat-related illnesses, including consuming alcohol and caffeine, according to Adkins. "Some medications can also make patients more susceptible to heat-related illnesses, such as beta blockers for chronic heart failure or blood pressure control," he says.

More for your wellness

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.