Emergency advice


  1. Move them to a cool place.
  2. Call 999.
  3. Wrap in a cool, wet sheet until temperature reduces to 37.5 ºC.
  4. Replace with dry sheet.

What is heatstroke?

Heatstroke is caused by a failure of the ‘thermostat’ in the brain which regulates the body’s temperature. This means the body is unable to cool down when it becomes too hot.

It could be caused by spending too much time in the sun, having a high fever, or from taking non-prescription drugs such as Ecstasy. It can also occur after heat exhaustion when sweating ceases.

Your priority is to cool them down as quickly as possible and get them to hospital.

Signs and symptoms

Look for:

  • headache, dizziness and discomfort   
  • they may be restless and confused   
  • hot, flushed and dry skin
  • becoming less responsive quickly   
  • pulse that’s full and bounding   
  • body temperature above 40°C (104°F).

What to do

  1. Quickly move the casualty to a cool place and remove as much of their outer clothing as you can. Call 999 or 112 for emergency help.

  2. Help them to sit down in a comfortable, supported position. Wrap them in a cool, wet sheet and keep pouring cold water over the sheet until their temperature falls to at least 37.5°C (measured under the armpit).

    If a sheet is not available, fan them or sponge them down with cold water.

  3. Once their temperature has come down to normal, replace the wet sheet with a dry one.

  4. While waiting for help to arrive, monitor their level of response and temperature.

    • If their temperature starts to increase cool them down again using the same method.
    • If they become unresponsive at any point, open their airway, check their breathing and prepare to give CPR.

Browse our first aid products:

CPR masks and face shields

CPR masks and face shields

Shop now


Our training courses:

First aid courses

First aid courses


Related first aid advice

How to do CPR on an adult

If an adult is unresponsive and not breathing normally, you need to call 999 or 112 for emergency help and start CPR straight away. Learn what to do.

How to do the primary survey

Use the primary survey to quickly assess the situation and check the casualty for injuries or conditions that could be immediately life threatening. Find out what to do.

When to call an ambulance

At some point in their life, most people will witness or be involved in an accident or medical emergency. Knowing what to do and when you should call the emergency services can potentially save lives.

St John Ambulance volunteers providing support