Heat kills more people than floods, storms and earthquakes, and it does it quietly. There is no wreckage to photograph and no single moment to report, so a heatwave passes and the deaths appear weeks later in mortality statistics. Most of them were preventable, and the difference usually came down to one thing: whether somebody recognised heat stroke early enough to act.
This guide explains how to tell heat exhaustion from heat stroke, what to do in each case, and who is at risk long before the temperature looks dangerous.
If someone is confused, has stopped sweating, or has collapsed in the heat, call emergency services now and start cooling them while you wait. Everything below explains why.
The one distinction that matters
Almost all confusion about heat illness comes from treating it as a single thing. It is two, and the response is completely different.
Heat exhaustion is the body struggling but still in control. The person is sweating heavily, feels weak, dizzy or sick, has a headache, cramps, clammy pale skin and a fast, weak pulse. They know where they are. Handled properly, they usually recover within half an hour and it ends there.
Heat stroke is the body's temperature control having failed. Core temperature climbs past about 40 °C (104 °F) and organs begin to be damaged. This is a medical emergency in the same category as a heart attack — untreated, it can kill within hours, and every minute at that temperature adds to the harm.
The signs that mean heat stroke, not exhaustion
These change the situation from "sit them down with water" to "call an ambulance":
- Confusion, slurred speech, or strange behaviour. This is the single most important sign. Heat is affecting the brain. Someone who cannot answer simple questions properly is not merely tired.
- Skin that is hot and dry, with sweating having stopped. The cooling system has quit. (Note: in heat stroke brought on by physical exertion, the person may still be sweating — do not use sweating alone to rule it out.)
- Seizures or loss of consciousness.
- Very rapid breathing and a strong, fast pulse.
- Skin that has turned red and flushed, or very hot to touch.
- Being no better after 30 minutes of resting in the cool with fluids. Heat exhaustion that does not improve is heat stroke arriving.
What to do: heat exhaustion
- Move them somewhere cool — shade, indoors, air conditioning if there is any.
- Lie them down and raise their legs slightly.
- Remove unnecessary clothing.
- Cool the skin: cool water on the face, neck, armpits and groin, and fan them. Wet cloths work.
- Give plenty of water to drink if they are fully alert. Sports drinks or oral rehydration salts help replace what was lost in sweat.
- Stay with them until they are properly better.
If they have not clearly improved in 30 minutes, treat it as heat stroke.
What to do: heat stroke
Every minute counts here.
- Call emergency services immediately. Do not drive around looking for a hospital first — start cooling while help is coming.
- Move them out of the heat and remove outer clothing.
- Cool them aggressively. If cold water immersion is possible — a tub, a pool, a water tank — that is the fastest method and it is what sports medicine uses. Otherwise soak them with cool water and fan continuously, and put ice packs or cold wet cloths at the neck, armpits and groin where large blood vessels run close to the skin.
- Keep cooling until help arrives or until they are clearly responding.
- Do not give anything to drink if they are confused, drowsy or unconscious — they can choke.
- Do not give paracetamol, aspirin or ibuprofen. Fever medicines do not lower temperature caused by heat, and can make things worse.
- If they are unconscious but breathing, place them in the recovery position.
Who is at risk earlier than everyone else
Heat does not affect people equally, and the fatalities are heavily concentrated in a few groups:
- Older adults, especially those living alone. The sense of thirst weakens with age, and many older people feel heat less accurately than their bodies are experiencing it.
- Infants and small children, whose bodies heat up several times faster than an adult's. A child must never be left in a parked car, even briefly, even with a window open — interior temperatures can rise past 50 °C within minutes.
- People working outdoors — construction, farming, street vending, deliveries — who cannot simply stop.
- People with heart, lung or kidney conditions, or diabetes.
- People on certain medications, including some for blood pressure, depression and allergies, which can interfere with sweating or fluid balance. Do not stop any medicine because of heat — ask a doctor.
- Anyone in a top-floor or poorly ventilated room, where indoor temperature stays high through the night. Nights matter as much as days: bodies recover from heat while sleeping, and when night temperatures stay high, that recovery does not happen.
Reducing the risk before it becomes an emergency
- Drink water regularly rather than waiting for thirst. Thirst arrives after dehydration has started.
- Shift hard physical work to early morning or evening, and avoid the hours around midday.
- Close curtains and shutters on the sunny side during the day; open windows at night if it is cooler outside.
- Cool showers, damp cloths on the neck, and a fan combined with wet skin all work. A fan alone in very high temperatures moves hot air and does little.
- Check on elderly neighbours and relatives daily during a heat event. This single habit prevents more deaths than any equipment.
- Never leave a child or an animal in a parked vehicle.
How we track heat events
Heat is unusual among the hazards we monitor because the official warnings are good but the consequences are almost invisible in real time. National meteorological services publish heat warnings that we collect continuously, so the alerts appear on the map as they are issued — but the deaths they cause are rarely reported as heat deaths at the time.
That is worth stating plainly: our heatwave tracker shows where dangerous heat is being officially warned about, not a casualty count. Anyone citing heat mortality should use national statistics offices, which publish excess-death figures months afterwards.
You can see what is being warned about right now on today's page, look up your own area from the city index, or check a specific country such as Pakistan. To be told when a severe event is recorded near you, set up free alerts. If you know of a heat-related incident that has not been reported, you can submit it and we will review it.
The short version
Heat exhaustion means sweating, weakness and a clear head — cool them down and give fluids. Heat stroke means confusion, collapse, or no improvement after 30 minutes — call an ambulance and cool them aggressively while you wait. Do not wait for a thermometer, and do not give fever medicine.
Check on the people who will not call you.
This guide follows widely published public-health advice from national health services and meteorological agencies. It is general information, not medical advice for a specific person. In an emergency, contact your local emergency number — in Pakistan, Rescue 1122.
