Heat Exhaustion vs Heat Stroke: First Aid and How to Stay Cool (2026)

Heat stroke is the one first aid emergency where minutes decide whether someone walks away or doesn't. The line is simple: if a person in the heat is confused, stops sweating, or has hot, dry skin, call 911 and start cooling them immediately. That is heat stroke, and it's a race. Heat exhaustion, the milder version, you can usually turn around at home in about 30 minutes. Everything below is how to tell the two apart, what to do for each, and how to stay cool when the air conditioning is out.

Heat is the deadliest weather hazard in the US. The CDC counted 2,302 heat-related deaths in 2023, the highest tally in decades and up sharply from the year before. In a typical year, heat kills more Americans than hurricanes, tornadoes, and floods combined. The worst version of the problem is a heat wave and a power outage at the same time, which is why heat illness spikes in the days after a big storm takes down the grid.

Heat Exhaustion vs Heat Stroke

	Heat Exhaustion	Heat Stroke
What it is	Overheating your body can still recover from	Cooling system has failed. Emergency
Core body temperature	100–104°F	Above 104°F
Sweating	Heavy, noticeable	Often stops; skin hot, red, and dry
Mental state	Dizzy, weak, headache, nauseated, still alert	Confused, slurred speech, seizures, fainting
Pulse	Fast and weak	Fast and pounding
Bottom line	Cool down and rest; better within 30 minutes	Call 911 now. Cool fast

Heat Exhaustion First Aid

Move to shade or air conditioning, ideally the lowest floor, since heat rises. Loosen or remove extra clothing. Cool the skin with wet cloths or a cool, not ice-cold, shower, and point a fan at yourself. Drink fluids in small sips: about 8 ounces of water or a sports drink every 15 to 20 minutes. Rest 30 minutes, then recheck.

If you are vomiting, can't keep fluids down, or are no better after an hour, get medical help; untreated heat exhaustion becomes heat stroke, faster in older adults and children.

Heat Stroke Is a Race

Call 911 first, then act while help is on the way:

• Move the person to shade or inside.
• Cool as fast as possible. Cold-water immersion is the best method if a tub, wading pool, or shower is available. If not, douse with cool water and fan aggressively.
• Put ice packs or wet cloths on the neck, armpits, and groin.
• Keep cooling until the person seems more alert. Standard guidance: cool toward about 102°F, then ease off to avoid shivering or overcooling.
• Do not give fluids by mouth to anyone confused or unconscious; they can choke. Hydration comes once they can swallow safely.

Cooling within 30 minutes of symptoms starting measurably improves the outcome. This is not wait-and-see.

Who Is Most at Risk

Older adults over 65, children under 4, pregnant women, outdoor workers, and athletes. So are people on certain medications: diuretics, beta-blockers, antihistamines, and some blood pressure and psychiatric drugs blunt thirst or sweating. That means these groups overheat at lower temperatures and reach heat stroke faster. Check on older neighbors and relatives during a heat wave, not after it.

Humidity is the amplifier. Sweat only cools you when it can evaporate, and humid air slows that down. The number to watch is the heat index, what a temperature actually feels like on humid days. The National Weather Service rates a heat index of 103–124°F as dangerous and anything over 125°F as extremely dangerous. On those days, move outdoor work to early morning and don't push through midday.

Staying Cool Without AC (and With No Power)

• Keep heat out during the day. Close blinds and curtains on east- and south-facing windows. Open windows at night when the temperature drops.
• Cool the body, not the room. A wet bandana around the neck, pulse-point cooling (wrist, neck, groin, ankle), and a cool evening shower all work. A damp cloth draped in front of a fan is a poor man's swamp cooler.
• Drink on a schedule, not on thirst: 8 ounces of water every 15 to 20 minutes while active in the heat.
• Know the fan limit. Standard fans only help while the air is cooler than your skin. The World Health Organization advises that above about 95°F, a fan can push hot air at you and speed dehydration, so move to shade or a cooler room instead.

When the grid is down, cooling becomes a power problem, and a small amount of power changes the math. A EcoFlow RIVER 3 Portable Power Station holds 245Wh and runs about $239. That will drive a typical 25-watt box fan for close to 10 hours through the hottest night, keep a CPAP going, or recharge phones and radios. It refills from a wall outlet, car, or solar panel.

Heat waves also strain the water system, and boil advisories or low pressure show up right when you most need to drink. If your tap is under a boil advisory, or you're sheltering with uncertain water, a filter keeps everyone hydrating without waiting on a pot to boil. The Sawyer Squeeze Water Filtration System filters roughly 100,000 gallons, fits in a pocket, and costs about $46. If you need a faster option for the whole family, the Katadyn BeFree Water Filter flows at about 2 liters per minute for around $60.

Cars Heat Up Fast

Never leave a child or pet in a parked car. On an 80°F day, the inside of a car rises about 20°F in the first 10 minutes and can pass 100°F within an hour. Cracking a window barely helps. If you see a child or pet locked in a hot car, call 911.

Heat Safety Checklist

• Know the line: core temperature above 104°F with confusion means 911 now
• Fan, water, and a shady or lower-floor room planned for outage heat
• A cooling cloth or spray bottle for pulse-point cooling
• 8 ounces of fluids every 15–20 minutes when active in the heat
• Older relatives and neighbors on a check-in list
• No kids or pets in parked cars, ever

Heat illness is survivable and mostly preventable. The tools are simple: shade, water, airflow, and knowing that 104°F with confusion is the line where you stop waiting and start calling.