Heat Stroke: Signs and How to Cool Now

Key takeaways

The deciding sign of heat stroke is CONSCIOUSNESS: confusion, rambling speech, behaving unlike themselves, a seizure, not rousing when called. Someone still awake and answering properly usually has heat exhaustion — milder, but still needing action.
The skin may be hot and dry, but it may also still be damp with sweat. “Sweating has stopped” is the classic sign, but its absence does not rule heat stroke out.
Call 115 and cool AT THE SAME TIME. According to CDC, cooling must not be delayed — do not wait for the ambulance to arrive before starting.
Give nothing at all, not even water, to anyone who is confused, vomiting or unconscious. Give no fever medicine. Do not rub alcohol or spirits on the skin.
Get them into the cool and take off outer clothing; immerse them in cool water if you can, and if you cannot, pour water over them, put cold wet cloths on the neck, the armpits and the groin, and fan them hard.

On a hot day, what separates someone merely worn out by the sun from someone in heat stroke is not the sweat or the temperature of the skin — it is CONSCIOUSNESS. Confusion, rambling speech, a seizure, being called and not rousing: that is an emergency. Call 115 (the emergency number in Vietnam) and start cooling at the same time, rather than sitting and waiting for the ambulance.

Do these in parallel, in this order. ① CALL 115 NOW, saying clearly «suspected heat stroke» and whether the person is confused or unconscious. ② GET THEM INTO THE COOL: shade, a room with air conditioning or a fan; take off outer clothing. ③ COOL THEM NOW, do not wait for the ambulance: immerse the person in cool water if you can — always with someone holding the head, never leaving them to soak alone; if you cannot immerse them, pour water over the skin, soaking the clothes as well, put cold wet cloths on the neck, both armpits and the groin, and then fan them hard. ④ GIVE NOTHING to drink while the person is confused, vomiting or unconscious. ⑤ Lay them on their side if they are vomiting or not awake, and stay beside them until the ambulance arrives; if they stop breathing or are only gasping, tell the dispatcher at once.

Recognising it: consciousness is the deciding sign

According to CDC, the signs of heat stroke include:

Confusion, slurred speech, rambling speech, behaving unlike themselves — this is the most important sign.
Hard to rouse when called, or unconscious.
A seizure.
A very high body temperature; skin hot, red, and either dry or still moist.
A fast, strong pulse, headache, dizziness, nausea.

Two things wrongly reassure families. The first is sweat: CDC records that the skin may be dry OR moist, so someone still wet with sweat may yet be in heat stroke. The second is the thermometer: a reading under the arm or in the ear does not tell you the temperature inside the body, and the documents give different figures. Do not make a number the condition for calling the emergency services; make it consciousness.

How it differs from heat exhaustion

Heat exhaustion	Heat stroke
Still awake, answering properly, knows where they are	Confused, rambling speech, seizure, not rousing when called
Pouring sweat, skin cool and pale, clammy	Skin hot and red, may be dry or still moist

Still alert and able to drink is the milder group, but it still means getting into the cool and being watched. The moment consciousness changes it has become heat stroke, and from then on it is an emergency.

What to do straight away: cool as fast as you can

CDC describes immersion in cool or cold water as the fastest way to bring the temperature down, and states plainly that cooling must not be delayed. At home, do whatever you can do immediately, in the order given in the box above — and keep changing the cloths, because a cloth that has warmed up has stopped working.

What must NOT be done

Do NOT give anything to drink while the person is confused, vomiting or unconscious — not water, not salt water. For heat stroke, CDC records that the person is given nothing to drink.
Do NOT give fever medicine. MedlinePlus states plainly that fever medicines such as aspirin or paracetamol (acetaminophen) are not for this situation: the heat here comes from the surroundings, not from a fever.
Do NOT rub alcohol or spirits on the skin; MedlinePlus lists this among the things not to do.
Do NOT give drinks containing alcohol or caffeine, and do not give salt tablets.
Do NOT let the person walk about or get to the car by themselves. Lay them down somewhere cool and cool them there.
Do NOT stop cooling in order to sit and wait for the ambulance, and if you have to drive them yourself, carry on cooling on the way.

When you must go to hospital

CALL 115 or go to emergency care NOW — cool at the same time as you call, do not wait — if during or after being out in the heat, working or exercising, there is ANY of the following: confusion, rambling speech, behaving unlike themselves · heavy drowsiness, hard to rouse, unconscious · a seizure · skin hot and red, whether dry or still moist · vomiting repeatedly, unable to keep a single sip of water down · fast breathing, a fast and strong pulse · urine the brown of strong tea, or being unable to pass urine, after exertion in the heat. — BE SEEN THE SAME DAY, do not leave it until tomorrow, if the person has come through the episode but still has a lot of tiredness, a headache, dizziness or nausea that is not easing, or is still passing scant, dark urine after drinking. Be seen early even with mild signs in older people, small children, anyone pregnant, and anyone with heart disease, kidney disease or diabetes. Heat stroke has no safe waiting period: the moment it turns for the worse cannot be predicted.

According to CDC, those most at risk are people aged 65 and over, newborns and small children, people with chronic illness, anyone pregnant, people working or exercising outdoors, and people living without air conditioning; CDC's material for professionals adds cardiovascular disease, kidney disease, diabetes, certain medicines, dehydration, and not yet being acclimatised to the heat.

One thing that is often overlooked: CDC warns that the temperature inside a parked car rises very fast from the first few minutes, even with a window left ajar — do not leave a child in a car, not even briefly.

Put plainly: heat stroke cannot be dealt with at home — the necessary action is to cool at once and then get the person somewhere they can be monitored and given fluids into a vein. With a sign in the box above, go in first and call afterwards. Y Te Xanh (GreenCare) comes in at the two ends on either side: a remote consultation when you are unsure whether you need to go in, and, after discharge, a doctor coming to the house to take the history and examine, with a nurse measuring the vital signs and giving recovery care at home.

This article passes on the recommendations of public health authorities — sources: the US CDC, and MedlinePlus at the US National Library of Medicine for the things that must not be done — and does not replace being examined in person. Citing CDC here does not imply that CDC endorses Y Te Xanh or our services.

Need personalised advice for your loved one? Call our hotline 094 368 81 15 (24/7) — calling to ask a question or to book costs nothing. GreenCare has doctors who come to examine, nurses who carry out doctor's orders (injections, infusions, dressing changes), remote consultation by video call, and a review of the medicines you are taking; an in-depth remote consultation, or any one after the first, is a paid service. For children we take examination and acute care only — not long-term care at home, and not newborns or expectant mothers. We confirm we have staff in your area and provide transparent pricing before we begin.

Sources

CDC — About Heat and Your Health
MedlinePlus — Heat Illness

Frequently asked questions

How do I know it is heat stroke and not just heat exhaustion?

Look at consciousness, not at the sweat or the thermometer. Someone with heat exhaustion is still awake, answers properly, knows where they are and can drink; their skin is usually cool, pale and clammy. Heat stroke adds confusion, rambling speech, behaving unlike themselves, a seizure, heavy drowsiness or unconsciousness. Once consciousness has changed, treat it as an emergency: call 115 and start cooling at once, and do not wait to see whether it eases.

If they are still sweating, surely it is not heat stroke yet?

Not necessarily. CDC records that the skin of someone with heat stroke may be hot, red, dry OR moist — meaning that still being wet with sweat rules nothing out. “Sweating has stopped” is the classic sign, so many people treat it as a requirement, and this is the easiest place to miss the diagnosis. If the person is confused or hard to rouse, call 115 even though the skin is still damp.

Should water or oral rehydration solution be given?

No, not while the person is confused, vomiting or unconscious — for heat stroke, CDC records that the person is given nothing to drink, and MedlinePlus states plainly that nothing is given by mouth, salt water included, to anyone who is vomiting or not awake. The reason is that the swallowing reflex is not safe at that point and liquid can go into the lungs. Someone fully alert who is only worn out by the heat can reasonably sip water.

Should fever medicine be given to bring the temperature down?

No. MedlinePlus states plainly that someone with a heat emergency is not to be given fever medicines such as aspirin or paracetamol. The heat in heat stroke comes from the surroundings and from the body losing its ability to shed heat, not from a fever, so the medicine does not address the problem. What does bring the temperature down is cooling from the outside: immersion in cool water, pouring water over the skin, cold wet cloths on the neck, the armpits and the groin, and a fan.

Do we wait for the ambulance before cooling, or cool first?

Cool at once, in parallel with calling. CDC states plainly that cooling must not be delayed, and describes immersion in cool or cold water as the fastest way to bring the temperature down. While one person calls 115, the other gets the patient into the cool, takes off outer clothing and starts cooling. If you immerse them, always have someone holding the head and never leave them to soak alone.

They have come round and are talking normally — is hospital still needed?

They still need to be assessed by a doctor. Heat stroke is an emergency, and CDC places urine the brown of strong tea after exertion in the heat in the group that needs medical care immediately, with blood tests — and that sign can appear when the person already looks better. Be seen the same day if a lot of tiredness, a headache, nausea, scant urine or dark urine remains.