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Heatstroke can be caused by exercising in hot weather conditions.

Heatstroke can be caused by exercising in hot weather conditions.
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Heatstroke is a medical emergency. Go to your nearest hospital emergency department or call triple zero (000) immediately and ask for an ambulance if you or someone else is experiencing symptoms.

What is heatstroke?

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

Heatstroke occurs when a person’s body temperature rises from about 37°C to above 40.5°C. It is sometimes called hyperthermia (not to be confused with hypothermia, which occurs when the body's temperature drops significantly).

Heatstroke needs immediate first aid to lower the body temperature as quickly as possible.

Dehydration and heat exhaustion are milder types of heat-related illness.

What are the symptoms of heatstroke?

The signs and symptoms of heatstroke include:

  • rapid pulse and fast, shallow breathing
  • trouble speaking, slurred speech
  • problems concentrating or coordinating movements
  • aggressive or strange behaviour
  • dizziness, confusion, seizures or loss of consciousness
  • sudden rise in body temperature
  • hot and dry and possibly red skin, possibly with no sweat
  • dry, swollen tongue
  • headache, nausea or vomiting
  • intense thirst

When should I see my doctor?

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

What causes heatstroke?

Heatstroke is caused by prolonged exposure to heat. You can get heatstroke inside or outside, including by exercising in the heat.

You are more likely than others to get heatstroke if you are:

  • over 75 or very young
  • pregnant or breastfeeding
  • overweight
  • working or exercising in hot conditions
  • affected by chronic diseases such as heart disease and diabetes
  • taking certain medications

How is heatstroke treated?

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

Meanwhile, give the person sips of cool fluid if possible and lay them in a cool shady place.

Lower their body temperature any way you can, for example by:

  • removing excess clothing
  • sponging or spraying them with water and fanning the damp skin
  • immersing them in cool water
  • placing cold packs under their armpits or groin, or on the back of their neck

If a person with suspected heat stroke is unconscious, place them on their side with their mouth down (to drain any fluid) and the chin up to prevent possible suffocation.

Do not give aspirin or paracetamol to someone with heatstroke since this may make things worse.

How can heatstroke be prevented?

Heatstroke is linked to dehydration, so in hot conditions:

  • Drink plenty of water – even if you don’t feel thirsty. Avoid hot or sugary drinks.
  • Keep cool – try to avoid direct sun. Wear a hat and lightweight, loose-fitting, cotton clothing.
  • Keep your house cool – close windows, shut curtains and blinds, and use air-conditioning if you have it.
  • Help others – visit or phone friends, family and neighbours who are more at risk. Keep children cool and give them lots to drink. Ensure pets have plenty of water and shade.
  • Have a plan – know who to call if you need help, and follow your doctor’s advice if you have any medical conditions.
  • Never leave babies, children or animals alone in a car.

Postpone or cancel any activities, or reschedule them to a cooler part of the day or a cooler location.

Check the Bureau of Meteorology for warnings about hot weather.

Complications of heatstroke

Heatstroke is a potentially life-threatening condition. The high body temperature in heatstroke can lead to organ damage, and can cause existing conditions to become worse. In extreme cases, heatstroke can lead to death.

Resources and support

To get advice on what to do next, call healthdirect on 1800 022 222 to speak with a registered nurse, 24 hours, 7 days a week (known as NURSE-ON-CALL in Victoria).

Other languages

Further information about heatstroke in other languages:

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

Last reviewed: March 2020

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