It's important to recognize the symptoms of heat exhaustion before it turns into heatstroke — here's why

Heat exhaustion is a warning sign that your body is overheating.Maxim Blinkov/Shutterstock
  • Heat exhaustion symptoms can include heavy sweating, rapid pulse or heart rate, clammy or pale skin, nausea, fatigue, headache or lightheadedness, and even fainting.
  • If you're experiencing the symptoms of heat exhaustion, you should cool yourself down, get into the shade or air conditioning, and drink lots of water.
  • To prevent heat exhaustion — and more dangerous heat illness like heatstroke — it's important to avoid exercise in the hottest parts of the day and stay hydrated when it's hot and humid.
  • This article was medically reviewed by Jason R. McKnight, MD, MS, a family medicine physician and clinical assistant professor at Texas A&M College of Medicine.

Heat exhaustion is a condition caused by extreme heat, and its symptoms include heavy sweating and a rapid pulse.

This can happen to anyone. But most often, heat exhaustion occurs when people exercise or work outdoors in hot or humid conditions.

"Your body temperature can increase about a degree for every five minutes of exercise you're doing," says Joshua Scott, MD, primary care sports medicine physician at Cedars-Sinai Kerlin-Jobe Institute.Advertisement

When it's hot outside, it's important to know how to prevent heat exhaustion, and treat any symptoms by cooling yourself down immediately.

Without treatment, heat exhaustion can develop into heatstroke, a more dangerous heat-related illness. Here's what you need to know to keep yourself safe and avoid heat-related illness.

Heat exhaustion symptoms

The major signs of heat exhaustion are:

  • Heavy sweating
  • Rapid pulse
  • Cool, clammy, or pale skin
  • Fatigue
  • Nausea
  • Headache
  • Lightheadedness
  • Fainting

You may also experience heat cramps, another type of heat-related illness that causes muscle spasms and can be a precursor to heat exhaustion.


To treat symptoms of heat exhaustion, it's important to cool yourself down immediately. If heat exhaustion symptoms don't improve within an hour or they get worse — such as losing mental clarity or unconsciousness — you need to seek immediate medical attention. Advertisement

These more severe symptoms can be indicators of heatstroke, a more dangerous heat-related illness that can be fatal.

Here's how to treat heat exhaustion before it becomes dangerous:

  • Get out of the heat and rest. Seek shade or get indoors — and preferably in air conditioning — if you can.
  • Hydrate. Sweating is how your body tries to cool itself down, but it causes you to lose fluids. To treat heat exhaustion, you need to replenish those fluids by drinking water. You can also try a sports drink like Gatorade for electrolytes, which are minerals that help you stay hydrated.
  • Use cool water. You can help bring your body temperature down by taking a cool bath or shower, spraying yourself with a garden hose, or by putting wet, cool cloths on your body.
  • Loosen your clothing. Remove any tight or unnecessary clothing if you notice symptoms of heat exhaustion. Multiple layers can trap heat and make it harder for your body to cool itself — light fabrics and loose clothing are always best when it's hot.

Risk factors

Heat exhaustion can happen to anyone, but those most at risk include children under four and people over age 65. Advertisement

That's because the central nervous system isn't fully developed or has lost its ability to regulate temperature as well as most adults, Scott says.

In addition, those who are newer to exercise — or have taken a long break from working out — are also at risk because their body won't be as accustomed to regulating temperature during physical activity.

"We know that we become more efficient at cooling ourselves the more we exercise," Scott says. "So going out and exercising for the first time in five or six months can actually predispose you to heat illness."Advertisement

Exercising in a hot, humid environment can also increase your risk for heat exhaustion. If you live somewhere like Florida or South Carolina where relative humidity levels can reach 60% to 80%, the sweat on your skin won't evaporate as much, and your body won't be able to cool itself as effectively.

Some medications, like antihistamines used to treat allergies or diuretics used to treat high blood pressure, may also affect your body's ability to sweat effectively or stay hydrated, and can predispose you to heat exhaustion, Scott says.

Talk with your doctor if you're worried that your medication may be causing heavy sweating, rapid pulse, lightheadedness, or nausea during high temperatures. Advertisement


If you're going to be exercising or working outside in the heat, here are three of the best ways to protect yourself:

1. Avoid the hottest part of the day

Some jobs, like working construction, may require you to be outdoors all day, but if you can, try to avoid being outside around 3 p.m. to 4:30 p.m., when temperatures are highest. If you're planning to go for a run, check the weather for the day, and if the high is more than 101 degrees Fahrenheit, choose a cooler time of day to be outside, like the morning or evening. Advertisement

2. Take frequent breaks

When you're in hot and humid conditions, Scott recommends taking a 10-minute break for every 40 minutes of exercise.

Exercising quickly raises your body temperature, and giving yourself time to rest can help your body adjust to these changes.

3. Stay hydrated

When you're dehydrated, your body can't produce enough sweat to cool down. Make sure to take a drink about every 15 to 20 minutes while you work out, Scott says. Advertisement

Overall, you should be consuming about 100 fluid ounces of liquid a day, even if you don't feel thirsty. You usually don't feel thirsty until you're already dehydrated, Scott says, so it's important to drink water throughout the day, and especially when you're working out.

"Dehydration can start to reduce muscle strength which can then reduce your body's ability to thermoregulate itself," Scott says. "So the problems start long before you get thirsty."

Read the original article on Insider