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Heat exhaustion vs. heat stroke: How to know and what to do

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Heat exhaustion and heatstroke can be dangerous. Know the warning signs, treatments and risks. It could save your life this summer.

Summer’s here, and in many parts of the country it’s going to be another scorcher. Summer 2021 was the hottest on record in the U.S.1 And experts predict that this summer will be hotter than average again.2

That’s good news for beach, lake and pool lovers. But it can be bad news for people with some medical conditions.3 Hot weather can make your other conditions worse. It can even cause problems with your medication

“Heat and humidity increase your risk of heat-related illness, especially if you’re out of shape and overweight,” says Neil Gokal, MD. He’s the medical director of clinical education for Southwest Medical, part of Optum, in Las Vegas. Even people without a medical issue and children may be at risk. “Most heat-related illness in the U.S. happens in athletes, especially American football players,” Dr. Gokal points out.

But you don’t have to be a big-time athlete to be in danger. Heat-related sickness can happen to anyone who isn’t careful. Symptoms may start without warning, so know the signs and help prevent an illness that could threaten your life.

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Heat exhaustion: how to recognize the signs

Sweating is your body’s natural, built-in cooling system. Healthy people who aren’t used to heat can sweat more than six cups of liquid in an hour on a super-hot day.4 That’s according to a report from the Institute of Medicine.

Heat exhaustion can happen when you lose too much water and salt. That makes your body overheat and struggle to cool down. You’ll start to notice symptoms like these5:

  • heavy sweating
  • cold, pale and clammy skin
  • fast, weak pulse
  • nausea or vomiting
  • muscle cramps
  • tiredness or weakness
  • dizziness
  • headache
  • fainting

How to treat heat exhaustion

Spring into action if you notice someone else with these symptoms — or if you have them yourself. If you cool off within 30 minutes, you can help prevent serious health issues. So your first step is to bring your body temperature down. Some strategies that work fast6:

  • Move to a cool place (in front of a fan or air conditioning).
  • Loosen your clothes.
  • Sip some water.
  • Place a cool, wet cloth on your skin.
  • Take a cool bath.
  • Spray water on your body with a mister.
  • Lie down and raise your feet.

When does heat exhaustion become heatstroke?

Heat exhaustion may not be serious, but it can quickly change into heatstroke if you’re not careful. “Heatstroke affects your nervous system. And it can have very serious results, including death,” says Dr. Gokal.

If a person isn’t getting better after about 30 minutes, heat illness has the potential to turn into fatal heatstroke. “When someone becomes confused or irritable, or starts having seizures, they need emergency medical attention,” says Dr. Gokal.

Besides heat exhaustion symptoms, signs of heatstroke include7:

  • Body temperature above 103º F
  • Dry skin that doesn’t sweat or skin that becomes very hot, sweaty and flushed
  • Strong, fast pulse
  • Confusion or slurred speech
  • Loss of consciousness

When signs of this serious form of heat illness appear, act fast.8 You should:

  • Call 911 right away.
  • Lower the person’s temperature. The faster someone with heatstroke can be placed in cold water, the less likely they’ll suffer damage to their organs, lasting disability or death. When the body temperature goes above 104º F, your heart, lungs, liver, kidneys and brain may all begin to shut down. You may slip into a coma.

If the person is awake and can swallow, give them water and sit them up so they don’t choke. Do not give them medications used to treat fever, such as acetaminophen or NSAIDS (ibuprofen). “They can worsen heat illness,” warns Dr. Gokal.

  • When a person becomes unconscious, don’t give them anything to drink, since fluids may enter the lungs.
  • Begin CPR if the person loses consciousness and shows no signs of breathing, coughing or movement.

Heatstroke could land you in the hospital, where it could take a few days to get better. You may notice changes in your body temperature for weeks. And with a severe case, full recovery can take a few months or even up to a year.

Some of the treatments provided at a hospital include7:

  • Putting drugs or fluids into the bloodstream
  • An ice bath
  • A cooling blanket
  • Medication to prevent seizures
  • Extra oxygen

When you get home, don’t exercise for at least a week, or until your doctor gives you the OK. After that, your doctor may want to test your liver and kidneys.

Who’s at risk of heat exhaustion and heatstroke?

Anyone can get heatstroke or exhaustion, but some people have a higher risk, including9:

  • Babies and children under age 4
  • Adults older than 65
  • People who are ill or on certain medications (such as blood pressure medicine or antihistamines, which can alter cardiac performance)
  • Those who are overweight may have a bigger risk of heat illness. “Someone who is obese or has large muscle mass may produce more heat than their body can release through sweating,” says Dr. Gokal.
  • People who are out of shape
  • Those who have certain genetic disorders or problems with their sweat glands10
  • People who are dehydrated or who used alcohol before physical activity
  • Being male
  • People who have an Asian-Pacific Islander background

How can you prevent heat exhaustion and heatstroke?

A few simple strategies can help keep you safe as the temperature outside rises9:

  • Skip hard physical activity in high heat.
  • Drink lots of water. The Centers for Disease Control and Prevention advises drinking one 8-ounce cup every 15 to 20 minutes when working in the heat.
  • Wear light, loose-fitting clothes.
  • Stay indoors or in shaded areas when it’s very hot.


  1. National Oceanic and Atmospheric Administration. Summer 2021 neck and neck with Dust Bowl summer for hottest on record. Updated September 13, 2021. Accessed May 20, 2022.
  2. The Weather Channel. Summer outlook update: Hotter than average conditions most likely in the Rockies, Plains, and Midwest. May 18, 2022. Accessed May 19, 2022.
  3. Centers for Disease Control and Prevention. Heat and people with chronic medical conditions. Updated June 19, 2017. Accessed May 19, 2022.
  4. Institute of Medicine Committee on Military Nutrition Research. Water requirements during exercise in the heat. Accessed May 19, 2022.
  5. Centers for Disease Control and Prevention. Warning signs and symptoms of heat-related illness. Updated September 1, 2017. Accessed May 19, 2022.
  6. Centers for Disease Control and Prevention. Frequently asked questions (FAQ) about extreme heat. Reviewed June 1, 2012. Accessed July 19, 2022.
  7. Centers for Disease Control and Prevention. Warning signs and symptoms of heat-related illness. Reviewed September 1, 2017. Accessed July 19, 2022.
  8. Centers for Disease Control and Prevention. Heat stress - heat related illness. Reviewed May 13, 2022. Accessed July 19, 2022.
  9. Centers for Disease Control and Prevention. Tips for preventing heat-related illness. Accessed May 25, 2022.
  10. Journal of Medical Genetics. Investigating the genetic susceptibility of exertional heat illness. August 2020. Accessed May 25, 2022.

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