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Heat Exhaustion

Heat exhaustion is a condition that develops during prolonged exposure to heat. It's more likely to occur during strenuous activity. This includes exercise or manual labor. Symptoms include a fast heartbeat, excess sweating, and extreme tiredness. They also include muscle cramps, headache, and weakness. Stomach cramps, nausea, and vomiting may also occur. The person may be lightheaded and dizzy, and may even faint.

Treatment for heat exhaustion involves cooling the body down and replacing lost fluids, electrolytes, and salts. Cooling may be done with fans, cool cloths, or a cool-water bath. Fluids are best replaced by drinking chilled electrolyte solution, a sports drink, or water. If a person is very dehydrated, confused, or unable to drink, they will likely need IV (intravenous) fluids.

Heat exhaustion can progress to a serious condition called heatstroke. So, it should be treated right away. There is one main difference between heat exhaustion and heatstroke. With heatstroke, the body loses its ability to control its temperature, which can rapidly rise to above 104°F. There are also problems with brain function. These include confusion, headache, seizures, and coma. Other organ, such as the kidneys, liver, or muscles may be affected. Heatstroke is life-threatening.

Home care

Continue to drink extra chilled fluids at home during the next 12 to 24 hours. Water, electrolyte solution, or sports drinks are advised. Don't drink alcohol or caffeine.

Preventing heat illness

  • Protect yourself from the heat. Wear lightweight, light-colored clothing and a broad-brimmed hat.

  • Drink plenty of fluids before and during activity.

  • Limit exercise in hot or very humid weather. If you have to be active in the heat, take frequent breaks to drink fluids and cool down.

  • Don't exercise when you are feeling ill.

  • Watch for symptoms of heat illness, such as exhaustion, excessive sweating, and lightheadedness. If any occur, move to a cool place, rest, and drink cool fluids. Lying down with your legs raised slightly can help you recover.

  • Don't drink alcohol or caffeine.

Follow-up care

Follow up with your healthcare provider, or as advised.

When to get medical advice

Call your healthcare provider right away if any of these occur:

  • You can't keep fluids down

  • Vomiting or diarrhea

  • Hot, flushed skin

  • Symptoms worsen or new symptoms occur

Call 911

Call 911 for any of these symptoms of heatstroke:

  • Confusion

  • Irrational behavior

  • Hallucinations

  • Trouble walking

  • Seizures

  • Passing out

  • Fever of 104°F (40°C) or higher, or as advised by your provider

Online Medical Reviewer: Eric Perez MD
Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Ronald Karlin MD
Date Last Reviewed: 12/1/2022
© 2000-2025 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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