| What it is | Moderate heat illness; fluid/salt loss |
| Signs | Heavy sweat, weakness, nausea, clammy skin |
| Mental status | Largely normal (vs heat stroke) |
| Response | Rest, shade, fluids, cool down |
Heat exhaustion is a moderate heat illness from overheating and fluid and salt loss, marked by heavy sweating, weakness, dizziness, nausea, headache, and cool, clammy skin while mental status stays largely normal. It’s a warning sign that can progress to life-threatening heat stroke, so prompt rest, shade, hydration, and cooling are essential.
This is general educational information, not medical advice. In an emergency, seek professional medical help.
Don’t let it escalate
Untreated, it can become heat stroke; both fall under hyperthermia and are worsened by dehydration.
Frequently asked questions
What are the signs of heat exhaustion?
Heavy sweating, weakness or fatigue, dizziness or lightheadedness, headache, nausea, muscle cramps, and cool, pale, clammy skin. Importantly, the person is still mentally coherent — confusion or collapse signals the far more dangerous heat stroke instead.
How do you treat heat exhaustion?
Stop activity and move to shade or a cool spot, lie down and elevate the legs, loosen clothing, and cool the body with water, fanning, and cool packs to the neck, armpits, and groin. Sip water or an electrolyte drink. Improvement should come within 30–60 minutes; if symptoms worsen or mental status changes, treat as heat stroke and seek emergency care.
What's the difference between heat exhaustion and heat stroke?
Heat exhaustion is serious but the body's cooling still works and the person stays mentally clear; heat stroke is a life-threatening emergency where temperature regulation fails, body temperature soars, and mental status is altered (confusion, slurred speech, collapse). Heat exhaustion can progress to heat stroke if not treated.
Sources
- Heat-related illness — CDC
- Heat illness — Wilderness Medical Society