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. 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. Below is how to tell the two apart, what to do for each, and how to stay cool without AC.

Heat is the leading weather-related killer in the US, according to the National Weather Service. The CDC recorded 2,415 heat-related deaths in 2023, the highest annual total on record and up sharply from the year before. In a typical year, heat kills more Americans than hurricanes, tornadoes, and floods combined. The worst version is a heat wave and a power outage at the same time, when heat illness spikes in the days after a 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	100–103°F	103°F or higher
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

The 103°F line follows CDC and NWS heat-illness guidance; in practice, confusion is the signal.

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: 8 ounces of water or a sports drink every 15 to 20 minutes, the pace both the CDC and OSHA set for hot work. 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. For help judging how serious it is, our doctor versus ride-it-out guide has the red flags.

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. The National Athletic Trainers' Association's recommended stopping point is about 102°F; ease off there 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.

Consensus guidance from the Korey Stringer Institute: cool below 104°F within 30 minutes of collapse. Outcomes track how long the body stays hot. This is not wait-and-see.

Who Is Most at Risk

The groups the CDC flags first: older adults over 65, infants and young children, 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. 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 evaporates, and humid air slows that down. The number to watch is the heat index, what the temperature feels like. 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)

Our staying cool without power guide has the full method; the essentials:

• 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. The ready-made version is a Sukeen 4 Pack Cooling Towels (40" x 12"): soak, wring, snap, and the fabric sits about 20 degrees below air temperature for hours. Four towels run about $11, so one hangs at your neck and the spares stay cold in the fridge.
• 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. That drives a 25-watt box fan for close to 10 hours through the hottest night, keeps a CPAP going, or recharges 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 one, 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 is rated for 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, per CDC heat-safety data, and keeps climbing from there. 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: confusion with a core temperature of 103°F or higher 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 103°F with confusion is the line where you stop waiting and start calling.