Cases of heatstroke have increased over the past few decades, and will continue to be a health concern as the global climate changes, cities expand and people live longer.
Overheating first carries a risk of heat exhaustion, which is not usually serious if you can cool down within 30 minutes, but left untreated it can lead to heatstroke -- a medical emergency.
What is heatstroke?
Heatstroke happens when your body is unable to cool itself effectively, resulting in a very high body temperature of above 40C (104F). It can cause serious damage to vital organs such as the kidneys if not treated immediately.
There are 2 types of heatstroke:
- classic heatstroke -- this most often affects people over 70 with an underlying health condition
- exercise-related (exertional) heatstroke -- this generally happens to young, healthy people who engage in heavy exercise when it’s hot and humid
When to see a doctor for heatstroke
Immediate care for heatstroke involves resting in a cool place for at least 30 minutes and drinking lots of water.
If you or someone else is still feeling unwell after this, you could call for an ambulance.
You should also seek care immediately if you or someone else have any of the following symptoms:
- a temperature of 40C or above
- not sweating even though you're too hot
- problems breathing, including shortness of breath or fast breathing
- dizziness or confusion
- a fit (seizure)
- loss of consciousness
Put the person in the recovery position if they have lost consciousness while waiting for the ambulance.
Once at hospital, doctors may adopt additional cooling measures such as spraying the skin with lukewarm water and blowing air over the moist skin with fans.
Who is at risk of heatstroke?
Anyone can get heatstroke, but some groups are more vulnerable, such as babies, toddlers and the elderly.
People who are already ill and dehydrated, such as from gastroenteritis, are also at more risk.
But other circumstances also increase the risk of developing heatstroke, so you may need to take precautions if you:
- have an underlying health condition that affects the body’s ability to regulate its temperature, such as heart disease
- have an inability to sweat properly (anhidrosis)
- take certain medications such as water tablets (diuretics) -- these increase the amount of water and salt expelled from the body as pee
- drink alcohol or use recreational drugs such as cocaine
- are an athlete or military recruit in training
A study of the 2003 European heatwave in France found that the risk of death increased significantly in people who were noted on hospital admission that they couldn’t produce urine (anuria), were in a state of prolonged unconsciousness (coma) or had heart failure.
Treatment for heatstroke
Treatment of heat exhaustion and heatstroke aims to rapidly decrease body temperature. You can do this by:
- evaporative cooling -- move to a cool place, lie down and raise your feet slightly, drink plenty of water (or sports drinks) and cool the skin with a spray of cool water and fanning
- taking a cool bath
- putting cold packs on your armpits and neck
- removing as much clothing as possible
If you’re still feeling unwell after trying any of these treatments, call an ambulance.
Read more about heat exhaustion and heatstroke, including how to prevent it.