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Heatstroke

7-minute read

Key facts

  • Heatstroke is a life threatening condition where your body overheats. It’s more common in hot, humid weather.
  • As well as nausea, dizziness, headache and muscle cramps, heatstroke can cause hot, dry, red skin and confusion, seizures and loss of consciousness.
  • If someone has heatstroke, try to cool them down while waiting for the ambulance, for example by moving them into a cool or shady place, removing excess clothing, and offering sips of cool drink.
  • Be prepared for hot weather, stay out of the sun and drink plenty of water.
  • Never leave children or animals alone in a car.

Heatstroke is a medical emergency. Call triple zero (000) and ask for an ambulance if someone is experiencing symptoms.

What is heatstroke?

Heatstroke is a life threatening condition in which your body overheats and can no longer maintain a healthy temperature. You can avoid heatstroke by taking precautions in very hot weather.

Heatstroke occurs when your body temperature rises from about 37°C to above 40°C. It is sometimes called hyperthermia.

Dehydration and heat exhaustion are milder heat-related illnesses. They can lead to heatstroke if they’re not treated.

Why is heatstroke an emergency?

Heatstroke needs immediate first aid to lower your body temperature as quickly as possible. If not, it can lead to organ damage and death.

The risk of death increases the hotter you get and the longer you are overheated.

Why might I get heatstroke?

Heatstroke is caused by prolonged exposure to heat. It can occur when your body absorbs more heat than it can get rid of by sweating. You can get heatstroke indoors or outdoors. It is more likely to occur in hot, humid weather.

You can get heatstroke if you work or exercise in hot conditions without good air flow and if you don’t drink enough water.

You are at higher risk if you are:

  • over 75 years old, or very young
  • pregnant or breastfeeding
  • overweight
  • not physically fit
  • homeless or isolated
  • wearing excess clothing
  • affected by a chronic health condition or an infection
  • taking medicines that cause dryness or make you sweat less

What are the symptoms of heatstroke?

If you have heatstroke, you will usually not be sweating. Your skin may be red, hot and dry.

Heat exhaustion is a milder heat-related illness that can lead to heatstroke if not treated, so it’s important to recognise the symptoms early. If you have heat exhaustion, you will usually be sweating a lot, and have pale, cool, damp skin.

Other symptoms of heat exhaustion include:

If heat exhaustion turns into heatstroke, you may notice these additional symptoms:

  • sudden rise in body temperature
  • dry, swollen tongue
  • intense thirst
  • slurred speech
  • problems coordinating movements
  • aggressive or strange behaviour
  • seizures
  • confusion and loss of consciousness

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What should I do if someone has heatstroke?

Heatstroke is a medical emergency. If someone has heatstroke, call triple zero (000) and ask for an ambulance.

While you are waiting for the ambulance, try to cool them down in any way you can.

  • Give them sips of cool fluid if they are conscious.
  • Lay them in a cool shady place.
  • Remove excess clothing.
  • Sponge or spray them with cool water or cover them with wet towels or clothing and fan their damp skin.
  • Put them in cool water or a cool shower.
  • Place cold packs on their cheeks, palms and soles.

If they are unconscious, place them on their side with their mouth down and their chin up. You may need to do CPR.

Do not give aspirin, ibuprofen or paracetamol to someone with heatstroke.

What should I do if I have heat exhaustion?

There are steps you can take to manage heat exhaustion, and avoid the complications of heatstroke.

  • Find a cool place to rest.
  • Drink cool water or a rehydration drink. Avoid caffeine and alcohol.
  • Take off excess clothing.
  • Have a cool shower or use cold packs.
  • Use a fan or air conditioning.

Call triple zero (000) and ask for an ambulance or go to your nearest emergency department if your symptoms don’t improve.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How can I prevent heatstroke?

In hot weather:

  • Drink plenty of water, even if you’re not thirsty. Avoid alcohol and hot or sugary drinks.
  • Keep cool — try to avoid direct sun and wear lightweight, loose cotton clothing.
  • If you go out, try to go before 11am or after 5pm, wear a hat and take water.
  • Keep your house cool — close windows and curtains during the day and keep them open at night. Use fans or air conditioning.
  • Have a plan — know who to call for help and ask your doctor what to do if you have any health conditions.

You can also take steps to prevent other people getting heatstroke:

  • When it’s hot, visit or phone friends, family and neighbours who are at risk, and check they’re ok.
  • Keep children cool and give them lots to drink.
  • Ensure pets have plenty of water and shade.
  • Never leave children or animals alone in a car, even with the air conditioning on or windows open.

You can check the Bureau of Meteorology website for warnings about hot weather.

For more information on staying well in hot weather, visit Beat the heat.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: July 2022


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