If someone is suffering from heat exhaustion, rehydration drinks can help. Illustration: Petra Röhr-Rouendaal, Where there is no artist (second edition).

Compiled by Zoe Burden

Periods of intense heat, known as heatwaves, are becoming more common because of climate change. When it is very hot, people can suffer from health problems such as dehydration, heat exhaustion and heatstroke. In 2015, thousands of people died in India and Pakistan during a heatwave.

Anyone can develop illnesses caused by the heat. However, the risk is higher for groups such as children, the elderly and people with certain medical conditions.

Heat exhaustion

Heat exhaustion can develop when someone is exposed to high temperatures and their body loses water and salt. It is less serious than heatstroke, but it can lead to heatstroke if it is not treated soon enough.

Symptoms of heat exhaustion vary, but may include:

  • sweating a lot
  • muscle cramps
  • tiredness and weakness
  • headache
  • nausea and/or vomiting
  • feeling faint or dizzy
  • feeling very thirsty
  • fast heartbeat
  • urinating less often and having darker urine than usual
  • low blood pressure
  • fast, shallow breathing.

Treating heat exhaustion

If someone is showing signs of heat exhaustion, you should:

  • Get the person to drink liquids. They should ideally drink water, juice or a rehydration drink.
  • Help them to lie down in a cool place.
  • Remove any unnecessary clothing.
  • If possible, give the person a cool (not cold) bath or shower. Otherwise, apply a cool, wet cloth to their skin, or wrap them in a cool, wet sheet. Keep these cloths wet.
  • Keep fanning their skin while it is moist. As the water evaporates, it will help their skin to cool down.
  • If you have cold packs, place these on their neck, armpits, groin and back.

If the person does not respond to this treatment within 30 minutes, seek medical help.


Heatstroke is less common than heat exhaustion, but it is much more serious. It happens when the body loses its ability to sweat and cool itself down, causing the body’s temperature to rise dangerously high. Heatstroke can have many of the same symptoms as heat exhaustion (see above), but may also include:

  • hot and dry skin with no sweating (or sweating that suddenly stops)
  • confusion
  • loss of consciousness
  • seizures (fits).

Heatstroke can cause death or permanent disability.

Treating heatstroke

If you suspect that someone may be suffering from heatstroke, seek medical help immediately. Any delay can be fatal.

While you are waiting for medical help to arrive (or while you are taking the person to a health centre), follow the advice (left) for treating heat exhaustion. In addition:

  • If the person is unconscious and vomiting, place them on their side and make sure there is nothing stopping them breathing.
  • If the person has a seizure, do not place anything in their mouth.

Staying healthy in the heat

Here are some simple steps to help protect yourself during very hot weather:

  • Stay indoors and avoid outdoor activities. If this is not possible, do these activities during the coolest parts of the day, and with other people. Always carry safe drinking water with you.
  • Drink plenty of fluids, and avoid alcoholic or very sugary drinks. In extreme heat, drink a cup of rehydration drink once or twice a day. You can buy packets of oral rehydration salts (ORS), but it can be much cheaper and just as effective to make your own. Mix 1 litre of safe drinking water with half a level teaspoon of salt and 6 level teaspoons of sugar. Someone with diarrhoea needs a cup of rehydration drink after every watery stool.
  • Wear loose, light-coloured clothing. If you go outside, cover your head.
  • Take cool showers or baths regularly. Sponge yourself with cool water throughout the day.
  • Eat cold foods, such as salads and juicy fruits.
  • Check on family and neighbours regularly, and ask others to check on you.

Adapted from Cathy Travis, Extreme heat & how to prevent heat-related illnesses (Interhealth), with reference to the UK’s National Health Service websites www.nhs.uk and www.nhsinform.co.uk

See www.interhealthworldwide.org for more details.

Zoe Burden