What's the Difference Between Heat Exhaustion and Heat Stroke?

What's the Difference Between Heat Exhaustion and Heat Stroke?

Knowing the difference could save your life - and those of your family

To the average person, heat exhaustion and heat stroke sound pretty similar. After all, they are both heat illnesses brought on by too much exposure to high temperatures. But there are some differences between the two, and most importantly, you need to understand is that one is a progression of the other.

Let's say you're out for a run on a day when the temperature (or heat index) exceeds 90° Fahrenheit (32.2° Celsius), and your leg muscles start to cramp. That's an early sign of the onset of heat illness, meaning your body is struggling to keep its core temperature from exceeding 98.6° F (37° C).

In other words, the cramping is your body's way of telling you to stop running. So what you need to do is stop running, get some place cooler, sip some water and rest. But what happens if you were to ignore the cramping and keep running? Your body would have to work even harder to regulate its core temperature, and it could eventually overheat.

Seeing the Signs and Recognizing the Symptoms

This is when mild heat illness can progress to heat exhaustion. According to the Centers for Disease Control and Prevention, the symptoms are:

  • Heavy sweating
  • Weakness
  • Cold, pale and clammy skin
  • Fast, weak pulse
  • Nausea or vomiting
  • Fainting

At this point, it's time seek treatment!

  • Stop all activity.
  • Get to a cooler location, ideally an air-conditioned building. If that's not possible, rest in a shaded area.
  • Lie down, elevate your legs above your heart and loosen your clothing.
  • Apply cool, wet cloths or cooling packs your skin, or take a cool shower or bath, if possible.
  • Sip water.
  • If there's vomiting and it continues, or if symptoms don't subside in an hour, it's time to seek medical attention immediately.

If you were to press on (without fainting), and your body temperature were to continue to rise, your heat exhaustion would then progress to heat stroke. If you don't stop and seek medical treatment at this point, your body temperature could reach or exceed 104° F (40° C), and you could end up with brain damage, organ failure or even die. Here are the symptoms:

  • High body temperature (above 103° F or 39.4° C)
  • Skin is dry in spite of the heat
  • Rapid and strong pulse
  • Throbbing headache
  • Dizziness, confusion, disorientation, or staggering
  • Unconsciousness

It's important to note that some people reach heat stroke without ever showing any symptoms of heat exhaustion. Keep an eye on yourself and your family, and when heat stroke symptoms start to show, call 911.

Prevent Heat Illnesses

When working or exercising outside when the temperature or the heat index exceed 90° F (32.2° C):

  • Pace yourself.
  • Keep plenty of cool water on hand, drinking two to four cups per hour.
  • Avoid sodas and other drinks with sugar.
  • Encourage those around you to keep drinking fluids.
  • Wear a hat with a large brim as well as loose-fitting, light-colored clothing.
  • If possible, save outdoor tasks and activities for early or late in the day, rather than during peak heat.

Children under the age of 4 are susceptible to heat illness because their bodies' ability to regulate temperature is not fully developed. Follow the above tips for children in your care, and never leave them in a parked car — even if you leave the windows open.

People older than 65 are also vulnerable because illness or medication can affect the body's ability to regulate temperature. During an extreme heat wave, make sure your elderly relatives have access to air conditioning. Even if they stay inside, a fan may not be enough.


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