10 warning signs of heat stroke

It’s a term you may also hear referred to as “sunstroke,” and it is clinically defined as when your core temperature soars above 40 degrees Celsius, along with central nervous system dysfunction, explains James Winger, MD, associate professor of family medicine.

Heat stroke can happen in two main ways. One is from exertion, when “exercise raises someone’s core body temperature and the systems that usually help the body cool back down don’t work,” says Dr Winger. For instance, high humidity may impair the body’s ability to cool itself off through perspiration – sweat. A second cause is due to environmental factors like being in a heat wave with no access to air conditioning, for instance.

This is by far one of the biggest signs of heat stroke. It’s actually similar to hypothermia (when the body temperature drops too low): Sufferers may begin to make poor decisions or not respond appropriately when asked a question. One example might be getting lost in a trail race because you can no longer properly navigate, says Dr Winger.

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Because your mental capacities are compromised, it’s rare that you’d recognise your own brain blips. But people around you can pick up on it. “It’s best to consider if the person is not behaving appropriately to the situation they’re in – this makes it more likely you’ll flag someone in the earliest stages of illness,” says Dr Winger.

Disorientation is physical, too. Dizziness or staggering are also signs of exertional heat stroke. Dehydration can mess with your equilibrium, so take time to stop and catch your breath, drink water and re-evaluate your activity game plan, if necessary.

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If you’re exercising and dealing with nausea, it could mean that the peanut butter toast you ate before heading out is just not sitting right with you. But if it’s a hot day (and you’re not acclimated to working out in the heat) and nausea hits, be wary of heat stroke. Be especially concerned if you vomit. Dr Winger says that at organised races, doctors in medical tents will have athletes lie down for a few minutes and, if rest doesn’t help them feel better, the doctors will suspect heat illness.

You’ll likely get a headache with heat stroke, and it’s an early warning sign since you’ll get it with heat exhaustion, according to Beaumont Health. But while you may be able to treat heat exhaustion by going indoors and turning up the air-conditioning, taking a cool shower, and drinking rehydrating, with heat stroke you have an emergency that requires a swift call to emergency services.

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It’s hot and you should be sweating buckets; if not, it may be a sign of heat stroke. However, this is more likely in non-exertional heat stroke and doesn’t often occur from exercise. “This is one sign that everyone knows but doesn’t actually happen as much as we think,” says Dr Winger. If you’re out there running and notice that there’s a layer of dry salt on your body, that’s actually an indication that your body is sweating as it should. The difference is when you’re not exercising but are enduring the heat and your skin stays dry.

Skin that’s red and hot is another indication that your body may be dangerously overheating. Now’s the time to take action to cool off before things progress.

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You’d assume that the end of the summer would be the worst time of year, but when it comes to exercise-induced heat stroke, it’s actually the beginning of the summer season or early fall that can be trouble – should an uncommonly hot day occur. “When your body acclimatises to hotter weather, you become a more efficient and voluminous sweater, which serves as a big defence against heat illness,” says Dr Winger. If your body isn’t used to the heat, take frequent breaks, sip water or a sports drink to thirst, and seek out shady routes.

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