Emergency advice

Heat exhaustion:

  1. Help them lie down out of the sun and raise their legs.
  2. Give them water to drink.
  3. Advise them to seek medical advice.

What is heat exhaustion?

Heat exhaustion is caused by a loss of salt and water, usually through excessive sweating. It develops slowly and usually happens to people who aren’t used to hot, humid weather.

Signs and symptoms

Look for:

  • a headache, dizziness and confusion
  • a loss of appetite and feeling sick
  • sweat with pale, clammy skin
  • cramps in the arms, legs and stomach 
  • a fast, weakening pulse and breathing.

What to do

  1. Help the casualty to a cool place, out of the sun and encourage them to lie down with their legs raised and supported.

  2. You then need to give them lots of water to drink.

    • You could also give them an isotonic sports drink or oral rehydration solution, to help replace the salt and fluid they have lost though sweating.
    • Do not mix regular cooking salt into water and give it to them to drink, this will make their condition worse.
  3. Monitor their level of response. Even if they recover quickly, suggest they seek medical advice.

    • If their condition seems to be getting worse, call 999/112 for emergency help.  

Related first aid advice


Dehydration can develop into a more serious condition if left untreated. Find out what to look for and what to do.


Sunburn is caused by over exposure to the sun, or a sunlamp or sunbed. Find out what to look for and what to do.


If someone has heatstroke, your priority is to cool the casualty down as quickly as possible and get them to hospital. Find out what to look for and what to do.

St John Ambulance volunteers providing support