Heat exhaustion vs heat stroke
Heat exhaustion brings heavy sweating, cool clammy skin, weakness, nausea and a headache, and eases with shade, loosened clothing and sips of water. Heat stroke is an emergency: very high body temperature, hot red skin, confusion, slurred speech or fainting. Call 911 for heat stroke and cool the person as fast as you can, with cold water or ice packs, while you wait.
About 10 minutes to learnSafety critical: tightly scoped, know when to call a professional
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How to do it
- Watch coworkers, teammates and yourself on hot days, especially in the first days of heat.
- For heavy sweating, weakness, dizziness or nausea, move the person into shade or air conditioning.
- Loosen or remove extra clothing and apply cool, wet cloths to the skin.
- Give sips of cool water if they are awake and not vomiting.
- Get medical help if they vomit, get worse, or are not better within an hour.
- For confusion, fainting, hot red skin or a very high temperature, call 911 immediately.
- Cool a heat stroke victim fast: cold water on the body, or ice packs at the neck, armpits and groin, and fan them.
- Do not give drinks to anyone who is confused or not fully awake.
Stop and call a professional if
- Call 911 for confusion, slurred speech, fainting, seizures or hot red skin with a very high temperature.
- Get medical care for heat exhaustion that does not improve within an hour.
- Take a certified class in first aid and CPR: this page is a refresher, not training or certification.
In an emergency, call your local emergency number, 911 in the US. Take a certified class to practice this with an instructor.
Common mistakes
- Letting someone who is confused rest in the heat.
- Giving large amounts of water quickly to someone who is vomiting.
- Waiting for sweating to stop before treating it as heat stroke; people with heat stroke can still sweat.
- Going back to work in the heat the same day.
Quick self-check
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Teach this to someone
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Teach: Heat exhaustion vs heat stroke
What to say
Heat exhaustion brings heavy sweating, cool clammy skin, weakness, nausea and a headache, and eases with shade, loosened clothing and sips of water. Heat stroke is an emergency: very high body temperature, hot red skin, confusion, slurred speech or fainting. Call 911 for heat stroke and cool the person as fast as you can, with cold water or ice packs, while you wait.
What to show, in order
- Watch coworkers, teammates and yourself on hot days, especially in the first days of heat.
- For heavy sweating, weakness, dizziness or nausea, move the person into shade or air conditioning.
- Loosen or remove extra clothing and apply cool, wet cloths to the skin.
- Give sips of cool water if they are awake and not vomiting.
- Get medical help if they vomit, get worse, or are not better within an hour.
- For confusion, fainting, hot red skin or a very high temperature, call 911 immediately.
- Cool a heat stroke victim fast: cold water on the body, or ice packs at the neck, armpits and groin, and fan them.
- Do not give drinks to anyone who is confused or not fully awake.
When to stop and call a professional
- Call 911 for confusion, slurred speech, fainting, seizures or hot red skin with a very high temperature.
- Get medical care for heat exhaustion that does not improve within an hour.
- Take a certified class in first aid and CPR: this page is a refresher, not training or certification.
The check question
Ask: Which sign points to heat stroke rather than heat exhaustion?
Related skills
- What to say when you call 911
- Signs of hypothermia and how to warm someone
- How to drink sensibly and know your limit
- Every skill in First Aid and Emergencies
Words on this page
Sources
- National resuscitation and first aid guidelines, 2025 guidelines. Checked September 28, 2026.
- National occupational heat illness guidance, current edition. Checked September 28, 2026.
Last reviewed . First published .