Heat exhaustion and heatstroke

What is it?

The body normally cools itself by sweating, and in very humid weather sweating may not be enough (MedlinePlus). When the body cannot release its heat, heat exhaustion and heatstroke become more likely (WHO).

Heat rash

• Skin irritation from heavy sweating that looks like red clusters of small pimples; it is more common in young children (MedlinePlus and CDC) and usually clears in seven to ten days if the skin is kept cool and dry (Saudi Ministry of Health).

Heat cramps

• Muscle pains or spasms during heavy exertion, usually in the abdomen, arms or legs, caused by losing salt and fluid through sweat; they can also be a sign of heat exhaustion (MedlinePlus and CDC).

Heat exhaustion

• Tiredness, dizziness, headache, nausea or vomiting, heavy sweating with pale, clammy skin, cramps, a high temperature and intense thirst (NHS).
• It usually does not need emergency help if the person cools down within 30 minutes, but untreated it can progress to heatstroke (NHS and MedlinePlus).

Heatstroke

• A life-threatening emergency: a very high temperature, hot skin, a fast heartbeat and breathing, confusion or loss of coordination, and possibly a seizure or loss of consciousness (NHS).
• Body temperature can rise above 41°C within minutes (MedlinePlus); the Saudi Ministry of Health cites a temperature of 40°C or higher.
• The skin may be dry and not sweating (NHS) or sweating heavily (CDC), so do not wait for sweating to stop before suspecting it.

Why it matters

WHO describes heatstroke as a medical emergency with a high case-fatality rate, and it can cause death or permanent disability if emergency treatment is not given (CDC).

Cooling the body strains the heart and kidneys; heat can worsen heart, lung, mental-health and diabetes-related conditions and can cause acute kidney injury (WHO).

With prolonged exertion in the heat, muscle breakdown (rhabdomyolysis) can occur; its signs include muscle pain and dark, tea- or cola-coloured urine, and it can cause an irregular heart rhythm and kidney damage (CDC).

WHO estimates about 489,000 heat-related deaths a year worldwide between 2000 and 2019. Yet the health effects of heat are predictable and largely preventable by following health guidance (Saudi Ministry of Health).

Key points

• Signs of heatstroke mean calling emergency services at once, as does still feeling unwell after 30 minutes of rest, cooling and fluids (NHS).
• For heat exhaustion: move the person somewhere cool, remove extra clothing, give water, a sports drink or rehydration solution, and cool the skin with water and a fan; they should improve within 30 minutes (NHS).
• Do not give fever medicines such as aspirin or paracetamol for heat illness, salt tablets, or drinks containing alcohol or caffeine (MedlinePlus).
• Give nothing by mouth to someone who is vomiting or unconscious (MedlinePlus).
• Never leave a child in a parked car, even for minutes or with a window open; the temperature inside can rise almost 20 degrees Fahrenheit in the first 10 minutes (CDC).
• Drink regularly: about a cup an hour and at least 2–3 litres of water a day according to WHO; light-yellow or clear urine usually means you are drinking enough (CDC).

How to put it into practice

First aid for heat exhaustion:

1. 1
   Move them somewhere coolInto the shade or an air-conditioned room, and raise their feet (MedlinePlus).
2. 2
   Remove extra clothingSuch as a jacket or socks (NHS).
3. 3
   Give fluidsPlenty of water, or a sports drink or oral rehydration solution to replace salt, if they are alert and not vomiting (NHS and MedlinePlus).
4. 4
   Cool the skinSpray or sponge with cool water and fan them; cold packs wrapped in a cloth under the armpits or on the neck also help (NHS).
5. 5
   Stay with themThey should improve within 30 minutes; if not, or if signs of heatstroke appear, call emergency services and keep cooling them while you wait (NHS).

To prevent it in summer:

• Avoid the sun at its strongest: the NHS says between 11am and 3pm, and the Saudi Ministry of Health advises pilgrims to avoid it between 10am and 4pm.
• Drink regularly without waiting to feel thirsty, and cut down on sugary drinks, caffeine and alcohol (Saudi Ministry of Health, CDC and NHS).
• Wear light-coloured, lightweight, loose clothing, avoid dark, heavy clothes that absorb heat, and use a wide-brimmed hat and sunglasses (NHS and Saudi Ministry of Health).
• Avoid strenuous activity in the hottest hours, rest often in the shade, and spend 2–3 hours somewhere cool during heatwaves (WHO and CDC).
• If you will do strenuous activity somewhere hot, exercise for an hour a day in the heat before you travel so your body adjusts (CDC).
• Fans: sources give different limits — the NHS says they can help below 35 degrees, while WHO says to use them only below 40°C and the CDC only below 90°F, because above that they can raise body temperature. With air conditioning, WHO suggests setting it to 27°C and adding a fan.
• Check on older people, people living alone and people who are ill during heatwaves (WHO and NHS).

After a heat illness, ask your doctor before returning to strenuous exercise and build up gradually (MedlinePlus).

Special groups

Most at risk: older people, especially those 65 and over; babies and children up to 5; pregnant women; people with heart, lung or kidney disease, diabetes or dementia; people living alone; people taking several medicines; and people who work or exercise outdoors a lot (NHS, WHO and CDC).

Some medicines, such as beta-blockers and diuretics, make temperature control harder (MedlinePlus); do not stop or change them without your doctor, and keep medicines out of hot places (CDC).

Outdoor workers: in the UAE, work under direct sunlight and in open places is not allowed from 12:30pm to 3pm between 15 June and 15 September every year, with specific exemptions (UAE government portal).

Fasting in the heat: the risk of dehydration rises when Ramadan falls in summer, especially for children, older people, people with diabetes or kidney disease and people working in the sun. Hamad Medical Corporation in Qatar advises 8 to 12 cups of water between iftar and suhoor, avoiding the sun and physical activity during the day and exercising after iftar; people with long-term conditions should consult their doctor before fasting. See fasting with a chronic condition.

Children rely on adults to keep them cool and hydrated; dress them in loose, light, light-coloured clothing and make sure they drink enough (CDC). See also fever in children.

Risks and cautions

Common mistakes:

• Giving fever medicines: MedlinePlus says not to give them for heat illness.
• Rubbing the skin with alcohol, or giving salt tablets or drinks with caffeine or alcohol (MedlinePlus).
• Giving fluids to someone who is unconscious or vomiting (MedlinePlus and Saudi Ministry of Health).
• Thinking a car is safe for a child if a window is open (CDC).
• Waiting for sweating to stop before getting help — heatstroke can happen with sweaty skin (CDC).

Sources differ on fluids in heatstroke: the Saudi Ministry of Health advises giving no liquids, MedlinePlus says sips only if the person is alert, and Hamad Medical Corporation advises water if conscious. All agree on giving nothing by mouth to someone unconscious or vomiting.

Limits of this information

The sources of this page give no body-temperature figure for heat exhaustion, and the figures for heatstroke differ between sources; the signs matter more than a single number.

We found no figures for heat illness cases or deaths in the UAE, Oman or Saudi Arabia in the sources of this page.

The sources do not say when to break a fast because of heat and do not cover religious rulings; ask your doctor about your condition and religious scholars about the ruling.

Emergency numbers differ between countries; use the «Emergency» button at the top of the page to find yours.

Common questions