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Heat exhaustion vs. heatstroke: signs and differences

August 25, 2022 • read

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Heat exhaustion vs. heatstroke: signs and differences

The dog days of summer might be waning, but that doesn’t mean the heat is. Summer lasts well into September, and temperatures often stay high right until its end. While this balmy weather feels like a treat after those long Canadian winters, it can also have a darker side. Scorching temperatures can leave you with heat exhaustion and even heatstroke.

Luckily, learning to recognize their symptoms can help you head off trouble before it’s too late. Here’s everything you need to know about heat exhaustion and heatstroke, including when to seek medical care.

What’s the difference between heatstroke and heat exhaustion?

Heat exhaustion and heatstroke are forms of hyperthermia, which is a fancy way of saying overheating. If you’re looking for medical advice regarding your heat-related symptoms, Maple can help. Maple is a telehealth platform that lets you connect with Canadian-licensed doctors and specialists from your phone, tablet, or computer

Heat exhaustion and heatstroke might sound the same, but the two are distinct conditions with some important differences. For starters, while heat exhaustion might make you feel faint, you don’t lose consciousness — that can happen with heatstroke, however. Another big difference lies in your temperature. If you have an elevated temperature but you’re still reading below 40°C (104°F), you’re likely dealing with heat exhaustion, not heatstroke.

Finally, and most importantly, while you can usually cope with heat exhaustion on your own, heatstroke requires medical intervention. It’s a medical emergency.

What are the symptoms of heatstroke and heat exhaustion?

While both conditions involve being too hot, distinguishing between the symptoms of heatstroke vs. those of heat exhaustion is crucial. Knowing that someone is experiencing heatstroke could mean saving their life.

Symptoms of heat exhaustion:

  • Heat cramps
  • Feeling very thirsty
  • Feeling tired and weak
  • Sweating profusely
  • Irritability
  • Pale, clammy skin
  • Nausea, vomiting
  • A slight increase in body temperature (below 40°C or 104°F)
  • Dizziness, a lack of coordination
  • Increased heart rate, normal blood pressure

Symptoms of heatstroke

If you or someone you love overheats and experiences any of the following, it’s a medical emergency.

  • Nausea and vomiting
  • Diarrhea
  • Confusion
  • Headache
  • Loss of consciousness, fainting, seizures
  • High body temperature of 40°C (104°F)
  • Rapid, shallow breathing
  • Increased heart rate, low blood pressure
  • Hot, red skin that’s either dry or clammy

What are the risks of heat exhaustion and heatstroke?

Heat exhaustion is uncomfortable as your body is in an extreme state of stress. If you’re not able to cool yourself down quickly, you run the risk of crossing over into heatstroke territory.

Heatstroke, in contrast, is life-threatening. It means that your body has lost its ability to cool itself down. This causes your internal temperature to rise, and the longer the body spends in an overheated state, the more damage is possible. Without medical intervention, this can affect your organ functioning, leading to organ damage and death.

What causes heatstroke and heat exhaustion?

As their names suggest, both conditions are brought on by being too hot. This is more likely to happen when you’re unused to high temperatures — like a sudden heat wave after a long winter, or when you’re on vacation, for example. Roasting in tropical temperatures isn’t their only cause though.

Overexerting yourself can also increase your internal temperatures faster than your body can cool you down. This makes exercising or working outside in high temperatures a common cause of heat exhaustion and heatstroke — a great reason to schedule those outdoor runs for early mornings.

Other factors that contribute to heat exhaustion and heatstroke include:

  • High humidity — as you sweat, your sweat evaporates, taking the excess heat energy your body produces with it. When there’s a high level of humidity, however, your sweat can’t evaporate as easily — if at all. Without the evaporative process, your sweat has nowhere to go, and all that heat stays put. This increases your chances of heat exhaustion or heatstroke.
  • Dehydration — this limits the amount of sweat your body can produce, leaving you unable to cool yourself down adequately.
  • Dressing inappropriately for hot weather — wearing tight garments or too many layers of clothing can cause your body temperature to rise more quickly.
  • Being elderly or very young. Infants, children, and the elderly all have more difficulty regulating their internal temperatures. They’re more susceptible to heat-related illnesses, more quickly than younger adults.
  • Drinking alcohol — beyond leading to dehydration, alcohol can also mess with your body’s temperature regulation abilities.
  • Having a pre-existing medical condition, or taking certain medications or drugs. Certain health conditions or substances can inhibit your body’s ability to control its temperature properly. Like alcohol, drugs, certain medications, and some medical conditions may also affect your judgment, leaving you at an increased risk of heat-related illnesses.

How do you treat heatstroke and heat exhaustion?

When it comes to heat exhaustion, your first priority should be to get out of the heat. Seek shade or indoor air conditioning, and take a moment to remove any excess clothing. If air conditioning isn’t available, you can cool your body down by applying a cold, damp cloth to your neck, groin, and armpits, or by taking a cool shower.

From there, replenish your fluid levels by slowly sipping water or another non-alcoholic and non-caffeinated beverage. Electrolyte loss can make heat exhaustion worse, so if they’re available, incorporating a sports drink or oral rehydration beverage is beneficial.

Unlike heat exhaustion, heatstroke is a medical emergency and shouldn’t be treated at home. Home remedies like drinking buttermilk don’t work. Others — like bathing in ice water — aren’t safe without medical supervision and can cause further damage. Every minute counts with heatstroke, and if you suspect you or a loved one is experiencing symptoms of heatstroke, they need immediate medical attention.

How to prevent heatstroke and heat exhaustion

Preventing heat exhaustion and heatstroke in the first place is extremely important. If you have to be outside on a hot day, make sure you stay hydrated and take frequent breaks. If you can, plan physically demanding tasks for earlier in the day or later in the evening. The hottest part of the day is usually between 3pm and 5pm — not between noon and 3pm as many believe.

During a heatwave, indoor air conditioning is pivotal in preventing heat-related illness. Spraying yourself with cool water and sitting in front of a fan can be helpful, but above 30°C (86°F) fans aren’t enough. If you don’t have air conditioning, taking a cool shower or bath is the next best thing.

If you’re still not getting relief, however, moving to an air-conditioned community space is the safest thing. Most municipalities run cooling centres during heatwaves, but libraries and coffee shops are great alternatives in a pinch.

Additional measures to take include:

  • Wearing sunscreen with an SPF 30 or more — a sunburn will make you feel even hotter
  • Drinking water and lots of it — even before you feel thirsty
  • Avoiding alcohol — while a cold beer on a hot day is refreshing, it’ll dehydrate you more quickly than water
  • Wearing loose, light-coloured clothing and a hat if you do go out
  • Drinking two to four glasses of fluids an hour if you have to work outside
  • Packing water-rich foods in your cooler — eating does help with preventing heat exhaustion and heatstroke if you’re drinking lots of water and eating items like watermelon, cucumber, celery, and kiwi.

Keep in mind that heatstroke can happen surprisingly quickly. Never leave small children or pets unattended in the car, even if you’re just popping in somewhere for a minute. Infants and children are especially susceptible to heat-related illnesses and even a few minutes in a hot car during high temperatures can result in medical distress.

How long can heatstroke and heat exhaustion last?

Recovery time from heat exhaustion can take up to half an hour, but you should start to feel better soon after getting treatment. Moving to a cool location and consuming fluids should clear up any nausea or profuse sweating rapidly.

While the tiredness and weakness might linger until you’ve had a chance to sleep and recuperate, your heart rate and skin texture should be within normal ranges within that half an hour or so. If you don’t experience a significant remission of symptoms within an hour, you should seek medical advice.

Heatstroke is another story. Because of its potential impact on your organs, recovery from heatstroke isn’t always clear-cut. Most people who experience exertional heatstroke tend to be younger, healthier individuals. It often happens to athletes or military recruits training in extreme temperatures.

In these cases, the worst physical effects are usually over within four days of their episode, and most make a full recovery in a little longer than two weeks. Those that end up with serious organ damage, however, may take longer or may never fully get better.

For those who experience classic heatstroke, the prognosis tends to be worse. Classic heatstroke is the result of exposure to extreme heat, and it’s more likely to happen to infants and children, or to the elderly who may be frail. The physical stress of heatstroke in these cases can take a very long time to recover from. Some may never fully “bounce back,” and others, unfortunately, succumb to their injuries.

When to see a doctor

If you don’t start feeling better within an hour of treating your heat exhaustion, you should speak with a doctor. Maple connects you with Canadian-licensed doctors remotely, when it’s convenient for you. This lets you see a doctor within minutes — which is crucial if you think your heat exhaustion may be morphing into something worse.

Maple doesn’t treat emergency issues, however, so if you’re experiencing symptoms of heatstroke, go to your nearest emergency room immediately.

Heat-related illnesses can happen quickly. But, knowing the symptoms of heat exhaustion and heatstroke can protect you from the worst. So get out and enjoy all that summer has to offer, just don’t forget to take precautions.

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