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What is the first aid for heat exhaustion?

Dr. Colin Little

Dr. Colin Little

MD, FAWM, Chief Medical Officer, GOES Health

The short answer

For heat exhaustion, move the person to a cool place, remove extra clothing, and cool them with cold compresses or cold water on the head, face, and neck. Give cool water to sip. Get medical help if they don't improve or get worse. If they turn confused or can't stay awake, treat it as heat stroke: call 911 and give nothing to drink.

Heat exhaustion responds well to quick, simple care. Get the person out of the heat to a cool spot, and take off extra clothing, including shoes and socks.1

Cool them with cold compresses, or have them wash their head, face, and neck with cold water, and give cool water to sip.1 Keep the water coming in small, frequent sips, and let them rest while the cooling takes hold. Fanning wet skin is one of the best and quickest ways to cool them12 while they rest.

If they don't improve, or they start getting worse, get medical help, and call 911 if no other care is available.1 Do not wait for the symptoms to pile up before you make that call.

One line you should not cross. If the person becomes confused or cannot stay fully awake, stop treating it as heat exhaustion. It is heat stroke. Call 911, cool them hard by wetting large portions of their skin and fanning them, and give them nothing to drink, since a drowsy person can choke on it.123

Sources

  1. [1] US Centers for Disease Control and Prevention / NIOSH. Heat-related Illnesses (NIOSH Heat Stress). Accessed August 6, 2026. https://www.cdc.gov/niosh/heat-stress/about/illnesses.html
  2. [2] US National Park Service. Hike Smart — Grand Canyon National Park. Accessed August 5, 2026. https://home.nps.gov/grca/planyourvisit/hike-smart.htm
  3. [3] Wilderness Medical Society / Wilderness & Environmental Medicine. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update. 2024. Accessed August 5, 2026. https://doi.org/10.1177/10806032241227924

About the author

Dr. Colin Little

Dr. Colin Little

MD, FAWM, Chief Medical Officer, GOES Health

  • Board Certified Emergency Physician
  • Fellow of the Academy of Wilderness Medicine (FAWM)
  • Wilderness Medicine Fellowship, University of Utah
  • Emergency Medicine Residency and Chief Resident, Stanford / Kaiser
  • Doctor of Medicine, University of Arizona College of Medicine – Phoenix
Keep reading

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What are the symptoms of heat exhaustion?

Heat exhaustion sets in when you lose too much water and salt through heavy sweating. Watch for a headache, nausea, dizziness, weakness, and thirst, with a fast, weak pulse. The reliable sign that it's still heat exhaustion, not heat stroke, is a clear head; confusion means heat stroke, even if the person is still sweating.

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How do you tell heat exhaustion from heat stroke?

What separates heat stroke from heat exhaustion is altered mental status, a change in how clearly the person thinks . Heat exhaustion leaves the nervous system uninjured, so the person still makes sense and can answer you . Heat stroke adds confusion, slurred speech, seizures or loss of consciousness . Treat that change as an emergency. Cool the person immediately and call for help .

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How much water should you drink when hiking in the heat?

On a hot hike, carry about a quart (roughly a liter) of water for every hour you'll be out, and let thirst tell you when to drink, since forcing down far more than you sweat out can be dangerous. On longer hikes, add salty snacks as well.

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