Why heat is dangerous
The body keeps its temperature steady mainly by sweating. In very hot weather, or during hard work in the heat, it can fail to lose heat fast enough and overheat. This is heat illness. It can begin with cramps and tiredness, and without help it can turn into heat stroke, which is life-threatening.
Heat illness is easy to miss at first, because people blame tiredness on a hard day, and it can get worse quickly. Heat stroke is not only for people working in the sun. It can also happen indoors, in a closed, stuffy room.
Who is most at risk
- Babies and young children, who cannot get away from heat on their own
- Older adults, who often feel less thirsty and may sweat less
- Pregnant and breastfeeding women, whose bodies work harder to stay cool
- People who work outdoors or in hot, badly ventilated places, such as construction and farm workers, street vendors and factory workers
- People with heart, lung or kidney disease, diabetes or another long-term illness
- People who take water pills (diuretics), sedatives or some heart and medicines, which can make it harder to cool down. Ask your doctor, and do not stop a medicine on your own
- People who drink alcohol, who are very overweight or underweight, or who live alone with no cool place to go
- Women who cook for long hours in a hot, closed kitchen
How to stay cool
Do
- Drink water often through the day, even when you are not thirsty, and carry a bottle when you go out.
- Buttermilk, fresh fruit juice and (ORS) help replace salts. If a doctor has limited your fluids, follow that advice.
- Stay indoors or in the shade from late morning to late afternoon. Do heavy chores and outdoor work in the early morning or evening.
- Wear light, loose clothes in light colours, and cover your head.
- Close windows and curtains on the sunny side by day. Open them in the early morning and evening.
- Cool your skin with a damp cloth, a water spray or a cool (not ice-cold) shower.
- Follow heat warnings on the radio, TV and phone, and check on older neighbours and anyone who lives alone.
Do not
- Do not leave a child, or a pet, in a parked car or any closed vehicle, even for a minute.
- Do not do hard physical work or exercise in the heat of the day.
- Avoid alcohol, and limit tea, coffee and sugary or fizzy drinks.
- Do not take salt tablets unless a doctor says so.
- Do not rely on a fan alone when the air is very hot. Wet your skin or clothes as well, and go somewhere cooler if you can.
Babies, pregnancy and outdoor work
Babies and children: dress them in light, loose clothes that cover their skin, with a wide-brimmed hat. Do not cover a pram with dry cloth. Use a thin wet cloth and keep it wet.
Pregnancy: drink water regularly, rest often and avoid hard physical work. Tell your doctor if you feel very thirsty, dizzy or have a headache, or a fast, weak pulse.
Outdoor workers: do the hardest work in the cooler hours, take breaks in the shade, drink water often and tell your supervisor if you or a co-worker feels unwell.
Signs of heat illness
Early signs, called heat exhaustion, include:
- Heavy sweating, with pale, clammy skin
- Tiredness, dizziness and a headache
- Feeling sick or being sick
- Cramps in the arms, legs or tummy
- Strong thirst
Heat stroke is more serious. Its signs include:
- Confusion, agitation or strange behaviour
- Very hot skin, which is often dry and flushed but can be sweaty after hard work
- A very high temperature and a very fast heartbeat
- Fainting or a fit (seizure)
What to do
If someone has signs of heat exhaustion:
- Move them to a cool, shaded place and have them sit or lie down.
- Loosen or take off heavy clothing.
- Give water or ORS to sip, a little at a time.
- Cool their skin with a wet cloth, a spray of cool water or a fan.
- Stay with them. They should start to feel better within about 30 minutes. If they do not, treat it as heat stroke.
If you think it is heat stroke, act at once:
- Call for an ambulance, or ask someone to, and say that it may be heat stroke.
- Move the person into shade or a cool room and lay them down.
- Take off heavy clothing, but do not delay cooling to undress them fully.
- Cool them straight away. Wet the whole body with cool water, using wet sheets, towels or a spray, and fan them. Ice packs on the neck, armpits and groin can help but should not be the only method.
- If they are awake and can swallow, give small sips of cool water.
- If they pass out, lay them on their side and check their breathing. If it is not normal, start CPR, as in the guide on hands-only CPR.
- Keep cooling them until the ambulance team takes over. Everyone with heat stroke needs hospital care.
Do not give paracetamol, aspirin or other fever medicines for heat stroke. They are not effective. Cooling the body is the treatment.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“I will drink water when I feel thirsty.”What is true?
Fact
Thirst comes late, and older people feel it less. Drink regularly through the day and do not wait to feel thirsty.
Myth“A cold drink, tea or coffee on a hot day is as good as water.”What is true?
Fact
Water is best. Alcohol, and too much tea, coffee or sugary and fizzy drinks, are better avoided in the heat. Buttermilk and fresh fruit juices are good choices unless your doctor has limited your fluids.
Myth“I will only be a minute, and the child will be fine in the parked car.”What is true?
Fact
Never leave a child or a pet in a parked vehicle, even briefly. A closed vehicle heats up fast, and young children cannot cool themselves or get out.
Myth“Heat stroke only happens to people who work in the sun.”What is true?
Fact
It can also happen indoors to older people, children and people with long-term illnesses, especially in a closed or unventilated room. The skin may be hot and dry, so lack of sweat does not mean the person is fine.
Common questions
How much should I drink in hot weather?
WHO advises drinking regularly through the day, about a cup an hour, and at least 2 to 3 litres a day in hot weather. Needs vary. If you have a heart or kidney problem and your doctor has limited your fluids, follow your doctor's advice.
Is a fan enough to keep me cool?
A fan helps most when your skin or clothes are damp. When the air itself is very hot, a fan alone may not be enough, so wet your skin, drink water, and rest in the coolest room you have or somewhere with shade or air conditioning.
Should I give paracetamol for the high temperature of heat stroke?
No. Fever medicines such as paracetamol and aspirin are not effective in heat stroke. The treatment is to cool the whole body quickly and to get the person to hospital.
Why do older people get heat illness without feeling thirsty?
Older people often feel less thirsty, and ageing skin and sweat glands do not cool the body as well. Medicines for the heart and blood pressure can add to the problem. They should drink regularly without waiting for thirst, and others should check on them in hot weather.