13 Heat Exhaustion Symptoms to Look Out For (2022)

Your body always wants to be as close to 98.6 degrees Fahrenheit as possible, and it usually does a pretty good job at regulating its own temperature. On a hot, humid day, though? Not so much.

When your body loses its ability to self-regulate, you run the risk of developing a heat illness, one of the biggest summer health hazards. Heat illness happens most often to people who are exercising or doing physical activity outdoors for long periods of time, to elderly people, and to people taking medications that increase their sensitivity to high temperatures. Given the right conditions, though, it can happen to anyone in high temps at any time of the year.

Here are the heat exhaustion and heatstroke signs and symptoms you should look out for.

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13 Heat Exhaustion Symptoms to Look Out For (1)

When your body has to work extremely hard to cool you down, you can develop heat exhaustion. During heat exhaustion, the body's core temperature is usually less than 104 degrees Fahrenheit, but blood pressure is low and the heart is not pumping blood as efficiently as it should.

At this stage, the body is still doing what it's supposed to. "You'll be very fatigued and sweating a lot and thirsty—so those natural defenses against heat and dehydration are still working," says Peter Shearer, MD, associate director of the Mount Sinai Hospital emergency department in New York City.

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Heat exhaustion does not necessarily lead to heatstroke—but it could, says exercise physiologist Michael Bergeron, PhD, president and CEO of Youth Sports of the Americas. Bergeron describes exertional heatstroke as "a clear medical emergency affecting multiple body systems," which usually occurs when the body's core temperature rises above 104 degrees.

Heatstroke causes the central nervous system to malfunction. It can also damage the brain, heart, liver, kidneys, spleen, and muscular tissue. "Your body loses the ability to thermoregulate, so at that point it's much more difficult to reverse itself," says Dr. Shearer.

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Warning Signs: Cramping, Nausea, or Headache

13 Heat Exhaustion Symptoms to Look Out For (2)

The first signs of a heat illness are often stomach cramping or nausea, which can indicate dehydration or an electrolyte imbalance in the body. These are closely linked with heat illness, since the body needs water (and electrolytes like sodium) to properly regulate its temperature, but it also loses them through sweat. Headaches are also a common first sign of dehydration.

It can be hard to pinpoint the exact cause of GI distress while you're exercising. "But, if conditions warrant you thinking this, best to assume that it is heat-related," says Bergeron. His advice? "Take a break [and] hydrate." Only if you're feeling better should you try going back to what you were doing.

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13 Heat Exhaustion Symptoms to Look Out For (3)

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"Heavy sweating is a sign that your body is producing a lot of heat," says Bergeron, which could lead to heat exhaustion if conditions don't improve, or if they worsen. In fact, heat is more dangerous on humid days, because sweat can't evaporate off the skin—which normally produces a cooling sensation—as easily as it can with dry or breezy weather.

Feeling thirsty is also a sign that your body needs more water. Even if you don't feel parched, it's important to sip water frequently on hot days. If you're out in the heat for more than an hour, a sports drink can also help replenish lost electrolytes. (Try one of these DIY sports drinks.)

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Warning Signs: Dark Urine

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Watch out for urine trouble. "If you're out playing tennis for hours but you're drinking between sets and you take regular bathroom breaks and your urine is fairly clear, that's a sign you're hydrating well," says Dr. Shearer. "But if you go for a long run and you're not urinating a lot, and when you do go it's very dark and concentrated, those are sign you're underhydrated. That means you won't be able to release heat as efficiently through sweat and evaporation, which puts you at risk for overheating."

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Heat exhaustion often makes people get dizzy, feel the need to sit down, or even pass out momentarily. "Which is sort of a good thing," says Bergeron: "That is, it stops your body from continuing before you get into more serious trouble."

The hotter it gets outside, the more common these symptoms are. But Bergeron says it's important to remember that, for people doing strenuous workouts, exertional heat illness can occur in relatively cool conditions, as well.

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Warning Signs: Lack of Sweating

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When the body reaches a certain internal temperature, its natural defenses—like sweating to release heat—begin to shut down. "If a person's been outside exercising in the heat and their skin is totally dry, that's a red flag," says Dr. Shearer.

However, says Bergeron, it's not always the case that a person will stop sweating as they enter the danger zone—so don't assume that just because someone is sweating heavily that they're okay. (If they have other signs of heat illness, get them help immediately.)

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If heatstroke progresses far enough, you can hurt your brain. "You start to experience confusion and delirium," says Dr. Shearer. "And that's really dangerous, because when you're confused you won't do the normal things to cool yourself down, like seek out shade or get water."

In the most severe cases of heatstroke, fainting and convulsions can occur.

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You Don't Have To Feel Hot

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The signs of heat illness aren't always as obvious as they might seem. "In fact, with developing overheating—possibly leading to exertional heatstroke—one can feel chilled, even in the heat," says Bergeron.

The reason? When the body experiences exercise- or heat-related stress (or both), it protects itself by producing inflammatory proteins. But these proteins can also interfere with the body's thermoregulation, bringing on symptoms like chills, goosebumps, or cold, clammy skin.

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Even if you do feel overheated, nauseous, or a little "out of it," it can be hard to stop what you're doing and take a break—especially if you're in the middle of a killer workout or running a race. That's why it's so important to recognize the earliest symptoms of heat illness and address them while you still can.

"A challenge is that an overheated athlete is often the worst person to make an objective assessment," says Bergeron. "As the body and brain heat up, the brain's cognitive capacity and objective reasoning are often compromised."

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What to Do: Listen to Your Body

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Most of the body's heat is generated internally, from muscle exertion. So in hot, humid conditions, it's smart to lower the intensity of your workout and take precautions beforehand—like wearing sweat-wicking clothing and drinking plenty of fluids.

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If you still feel like you're starting to overheat, stop what you're doing, says Bergeron. In fact, he adds, any significant deterioration in performance or signs of struggling should be reason to take a break.

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One of the most important things you can do for yourself or someone else who may be suffering from heat illness is to get them out of the sun. If you can, get to an air-conditioned area, but anywhere with shade can help. According to the U.S. Occupational Safety and Health Administration, a location that's bathed in direct sunlight can have a heat index value up to 15 degrees higher than a spot nearby in the shade.

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What to Do: Increase Air Circulation

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One way the body cools down is through convection—the process of air or water flowing across the skin and transferring away heat. You can help this process along by increasing air circulation and the air's exposure to skin, says Dr. Shearer.

"If someone is overheating, you can loosen their clothing—make sure nothing's too restrictive, or remove items they don't need," he says. Putting them in front of a fan, manual or electric, can also help them lose some of their excess body heat.

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Blood flow throughout the body can be compromised during a heat illness, so sitting or lying down with feet elevated about 12 inches can help prevent swelling in the legs and improve blood flow to the brain. It can also protect you from falling and injuring yourself if you're feeling faint.

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What to Do: Drink Cold Water, and Use It To Cool Your Body

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If a person is conscious and able to swallow, have them drink water or a sports drink that contains electrolytes. (Cold or cool fluids will help bring body temperature down faster than room-temperature ones.) You can also make your own electrolyte solution by mixing a teaspoon of salt per quart of water. This will help replenish sodium the person has lost through sweat. Sip until you're feeling better.

You can also use cold water or ice directly on the skin. If the person's not sweating, spritzing them with water can help mimic the process and help them evaporate some of the heat off of their body.

For someone whose body temperature has reached dangerous levels, full-body immersion into an ice bath or a cold body of water is the most effective method of bringing temps down quickly, says Bergeron. Applying ice packs or cold-water-soaked towels to the body can also help.

The groin and armpits are especially effective spots for cooling, says Dr. Shearer. So is the neck, although he cautions against putting ice packs directly on this area, since the carotid artery supplies blood to the brain.

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If a person is showing signs of heatstroke, get them medical care immediately. They should have their blood pressure, temperature, heart and respiratory rate, and central nervous system status monitored closely, even once they start to feel better.

Heat exhaustion, on the other hand, may not need professional attention. "If it's a person who is young and healthy and they're really sweaty and thinking clearly, they will probably be fine after cooling down and resting," says Dr. Shearer. "It's really the people who are older or who have other medical problems—heart disease, diabetes—who you want to get to a hospital to be safe."

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Take It Easy Afterward

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Even if you're young and healthy, that doesn't mean you should jump right back into your marathon or finish up your shift doing manual labor in the hot sun after a heat-illness scare. "You may still be measurably dehydrated and/or at risk for rapidly overheating if you go at it again," says Bergeron.

In fact, anyone experiencing heat illness should take the rest of the day off from physical exertion, he adds, even if your symptoms go away and you're feeling 100% better. "Best to rest and more fully recover, and live to play another day."

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Heatstroke can be dangerous, even fatal, and it can be difficult to treat once it sets in. That's why it's important to prevent it from happening in the first place. Avoid situations that put you at risk: don't push yourself too hard in the heat when you're recovering from an illness involving vomiting, diarrhea, or fever, taking medications that may make you more sensitive to heat or to the sun, or—of course—it's really hot out. Gradually ramping up your workouts over several weeks to acclimate your body to higher temperatures can also protect you during the summer.


What are the symptoms of heat exhaustion? ›

The signs of heat exhaustion include:
  • tiredness.
  • dizziness.
  • headache.
  • feeling sick or being sick.
  • excessive sweating and skin becoming pale and clammy or getting a heat rash, but a change in skin colour can be harder to see on brown and black skin.
  • cramps in the arms, legs and stomach.
  • fast breathing or heartbeat.

What are 5 symptoms of heat exhaustion? ›

What are 3 signs of heat exhaustion being too hot? ›

Weak, rapid pulse. Low blood pressure upon standing. Muscle cramps. Nausea.

What are 3 common signs symptoms to watch for when exercising in the heat heat stress? ›

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

What 6 things should you look for to identify heat stroke? ›

Heatstroke signs and symptoms include:
  • High body temperature. A core body temperature of 104 F (40 C) or higher, obtained with a rectal thermometer, is the main sign of heatstroke.
  • Altered mental state or behavior. ...
  • Alteration in sweating. ...
  • Nausea and vomiting. ...
  • Flushed skin. ...
  • Rapid breathing. ...
  • Racing heart rate. ...
  • Headache.
Jun 25, 2022

What happens to your body during heat exhaustion? ›

Heat exhaustion happens when your body overheats and can't cool itself down. It usually results from physical activity in hot weather. Symptoms include dizziness, confusion and nausea. They usually improve by drinking water and resting in a cool place.

What are the 4 types of heat illness? ›

Exposure to abnormal or prolonged amounts of heat and humidity without relief or adequate fluid intake can cause various types of heat-related illness. Children and teens adjust more slowly than adults do to changes in environmental heat.
What are heat-related illnesses?
  • Heat cramps.
  • Heat exhaustion.
  • Heat stroke.

Which two heat illnesses feature cramps as one of the symptoms? ›

Painful muscle cramps in the legs, arms or abdomen, known as heat cramps, may be the first sign of a serious heat-related illness and can be a symptom of heat exhaustion or heat stroke. Heat cramps occur most often after exercise in hot environments.

How long can heat exhaustion symptoms last? ›

Recovery time

In most people, symptoms of heat exhaustion will start to improve within 30 minutes. However, if symptoms do not improve after 30–60 minutes, seek medical attention. A doctor will treat heat exhaustion with one or two liters of intravenous (IV) fluids and electrolytes.

Does heat increase blood pressure? ›

Hot temperatures cause increased blood flow to the skin and dehydration, which can lower blood pressure significantly and lead to dizziness, fainting and falls, all of which are more dangerous in older adults.

Can being too hot make you vomit? ›

Heat exhaustion occurs when a person exercises and works in a hot environment and the body cannot cool itself adequately. Dehydration occurs with water loss from excessive sweating, which causes muscle cramps, weakness, nausea, and vomiting.

What is the first aid treatment for heat exhaustion? ›

Remove tight or heavy clothing. Have the person sip chilled water, a decaffeinated sports drink containing electrolytes or other nonalcoholic beverage without caffeine. Cool the person by spraying or sponging with cool water and fanning. Monitor the person carefully.

What should you do for a person who shows signs of heat stroke? ›

Seek emergency medical care
  • Put the person in a cool tub of water or a cool shower.
  • Spray the person with a garden hose.
  • Sponge the person with cool water.
  • Fan the person while misting with cool water.
  • Place ice packs or cool wet towels on the neck, armpits and groin.
  • Cover the person with cool damp sheets.

Do and don'ts of heat stroke? ›

While travelling, carry water with you. Avoid alcohol, tea, coffee and carbonated soft drinks, which dehydrates the body. Avoid high-protein food and do not eat stale food. If you work outside, use a hat or an umbrella and also use a damp cloth on your head, neck, face and limbs.

How do I cool down my body temperature? ›

Tips to reduce body temperature
  1. Drink cool liquids. ...
  2. Go somewhere with cooler air. ...
  3. Get in cool water. ...
  4. Apply cold to key points on the body. ...
  5. Move less. ...
  6. Wear lighter, more breathable clothing. ...
  7. Take heat regulating supplements. ...
  8. Talk to a doctor about thyroid health.

How often should you drink water on a hot day? ›

Dehydration is a primary contributor to heat exhaustion. Your work performance may suffer when you are dehydrated, even if you don't notice. When working in the heat, drink 1 cup (8 ounces) of water every 15–20 minutes. This translates to ¾–1 quart (24–32 ounces) per hour.

What are the harmful effects of heat? ›

Extreme heat events can be dangerous to health – even fatal. These events result in increased hospital admissions for heat- related illness, as well as cardiovascular and respiratory disorders. Extreme heat events can trigger a variety of heat stress conditions, such as heat stroke.

What is the most common heat-related illness? ›

Of all the heat-related illnesses, heat exhaustion is the most common. It's also a serious type of heat-related illness that should be addressed as quickly as possible. Heat exhaustion is caused by the body's extreme depletion of water and salt.

How long does it take to recover from heat exhaustion? ›

Recovery time

If fluids and rest do not resolve symptoms, a doctor will perform a blood work-up and other clinical tests to rule out other potential causes. If heat exhaustion is treated promptly, the individual will be fully recovered within 24-48 hours.

What is the fastest way to recover from heat exhaustion? ›

A bath of cold or ice water has been proved to be the most effective way of quickly lowering your core body temperature. The quicker you can receive cold water immersion, the less risk of death and organ damage.
  1. Rest in a cool place. ...
  2. Drink cool fluids. ...
  3. Try cooling measures. ...
  4. Loosen clothing.
Jul 1, 2021

Can heat stroke happen hours later? ›

Heat exhaustion or heatstroke can develop quickly over a few minutes, or gradually over several hours or days.

How do you get rid of heat exhaustion? ›

Lay the person down and elevate the legs and feet slightly. Remove tight or heavy clothing. Have the person sip chilled water, a decaffeinated sports drink containing electrolytes or other nonalcoholic beverage without caffeine. Cool the person by spraying or sponging with cool water and fanning.


1. How to tell when your dog is having a heat stroke
(FOX 13 Tampa Bay)
2. How to prevent heat exhaustion during hot weather
(WBIR Channel 10)
3. Exertional Heat Injury Prevention, Recognition & Treatment
(Los Angeles County Fire Department)
4. Safety Toolbox Talks : Heat Stress
5. Heat Stress - Rob Eirich - May 13, 2016
(Market Journal)
6. Emergency First Aid at Work V13
(Dave Summers)

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