Heat exhaustion and heat stroke are points on the heat-illness spectrum. In heat exhaustion the body is overheated but its cooling still works and the mind stays clear; in heat stroke that cooling fails, temperature soars, and mental status is altered — a true medical emergency. Recognizing the shift between them can save a life.
| Aspect | Heat Exhaustion | Heat Stroke |
|---|---|---|
| Severity | Serious but not immediately fatal | Life-threatening emergency |
| Mental status | Normal / coherent | Altered (confusion, collapse) |
| Body temperature | Elevated | Very high (often >104°F/40°C) |
| Skin | Cool, pale, clammy, sweaty | Hot; sweaty or dry |
| Response | Rest, shade, fluids, cooling | Aggressive cooling + immediate evacuation |
It's heat exhaustion if…
- The person is sweaty, weak, and nauseated
- They're still thinking clearly
- Skin is cool and clammy
It's heat stroke if…
- They're confused, slurring, or unconscious
- Body temperature is very high
- Behavior is irrational or they collapse
Verdict
Frequently asked questions
What's the difference between heat exhaustion and heat stroke?
Heat exhaustion is overheating where the body's cooling still functions and the person stays mentally clear, with heavy sweating, weakness, and nausea. Heat stroke is the failure of that cooling, with very high body temperature and altered mental status — confusion, collapse, or unconsciousness — and is a life-threatening emergency.
How can you tell heat exhaustion is becoming heat stroke?
Watch mental status: the transition to heat stroke shows as confusion, agitation, slurred speech, irrational behavior, seizures, or loss of consciousness, often with skin that's hot to the touch. Any of these signs means stop treating it as heat exhaustion and respond to a heat stroke emergency.
How do you treat each one?
For heat exhaustion: stop, move to shade, lie down with legs elevated, cool the body, and sip water or electrolytes — recovery should follow within an hour. For heat stroke: call for rescue and cool aggressively right away (cold-water immersion if possible, or dousing, fanning, and ice to neck/armpits/groin), then evacuate to medical care.
Related: Heat Exhaustion · Heat Stroke · Hyperthermia · Dehydration · Sun protection