Heat Exhaustion and Heat Stroke: A Beginner-Friendly Start
Heat Exhaustion and Heat Stroke: the few things that matter most, and the mistakes that catch people out early.
Two heat-related illnesses: heat exhaustion, which is a warning sign, and heat stroke, which is a medical emergency.
Key takeaways
- Heat exhaustion signs: heavy sweating, cold, pale and clammy skin, fast weak pulse, nausea or vomiting, muscle cramps, tiredness, dizziness, headache, fainting
- Heat stroke signs: body temperature of 103°F (39.4°C) or higher, hot red skin that may be dry or damp, fast strong pulse, confusion, losing consciousness
- Most useful single change: Stay in air conditioning during the hottest part of the day; use a cooling center if you need one.
- Commonest mistake: Leaving anyone, including children and pets, in a parked car.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
Why bother
Extreme heat is a leading weather-related cause of death in the US, and heat exhaustion can turn into heat stroke quickly.
Start here
Two to start. There is no prize for doing all of it in week one.
- Stay in air conditioning during the hottest part of the day; use a cooling center if you need one
- Drink more water than usual, without waiting until you are thirsty
Then add these
Once the basics are in place, add these.
- Wear loose, lightweight, light-colored clothing
- For heat exhaustion, move to a cool place, loosen clothing, use cool wet cloths and sip water
The numbers, in one place
| Measure | Figure |
|---|---|
| Heat exhaustion signs | heavy sweating, cold, pale and clammy skin, fast weak pulse, nausea or vomiting, muscle cramps, tiredness, dizziness, headache, fainting |
| Heat stroke signs | body temperature of 103°F (39.4°C) or higher, hot red skin that may be dry or damp, fast strong pulse, confusion, losing consciousness |
| Heat stroke | call 911; it is a medical emergency |
| Fans | when temperatures are in the high 90s °F, fans alone will not prevent heat illness |
| Higher risk | adults 65 and older, young children, outdoor workers, and people with chronic illness |
Common early mistakes
- Leaving anyone, including children and pets, in a parked car
- Heavy outdoor activity in the hottest part of the day
- Giving a person with heat stroke anything to drink
Related topics
- Sun and Heat Abroad: What the Evidence Actually Says (Travel Health)
- The Evidence on Burns and Scalds, Without the Hype (Emergency Care)
- Stroke: What Published Guidance Supports (Brain Health)
- The Evidence on Fever, Without the Hype (Immunity)
Where to go next
- Heat Exhaustion and Heat Stroke: What the Evidence Actually Says
- Making Sense of Heat Exhaustion and Heat Stroke
- Heat Exhaustion and Heat Stroke — the reference entry
- Weather Safety: The Complete Guide
- Heat and Medications: What Published Guidance Supports
- Hypothermia: What Published Guidance Supports
When to speak to a doctor
Call 911 for signs of heat stroke such as a temperature of 103°F or higher, confusion or passing out, then move the person somewhere cooler and cool them with wet cloths or a cool bath. Get medical help for heat exhaustion if the person is vomiting or symptoms get worse or last longer than 1 hour.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
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