What is heatstroke?
Heatstroke occurs when a person’s body temperature rises from about 37°C to above 40.5°C. It is sometimes called hyperthermia.
Heatstroke needs immediate first aid to lower the body temperature as quickly as possible.
Dehydration and heat exhaustion are milder types of heat-related illnesses.
What causes heatstroke?
Heatstroke is caused by prolonged exposure to heat. You can get heatstroke inside or outside. You can get it exercising in the heat.
You are more likely than others to get heatstroke if you are:
- over 75 or very young
- pregnant or breastfeeding
- living alone, homeless or lacking social support
- working or exercising in hot conditions
- affected by chronic diseases such as heart disease and diabetes
- taking certain medications.
The signs and symptoms of heatstroke include:
- rapid pulse and fast, shallow breathing
- trouble speaking, concentrating or coordinating movements
- 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
- nausea or vomiting.
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 as they may make things worse.
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. Never leave babies, children or animals alone in a car.
- Have a plan – know who to call if you need help, and follow your doctor’s advice if you have any medical conditions. 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.
Last reviewed: December 2015