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Heat exhaustion or heat stroke: What to do in an emergency

Hannah Fuchs
May 30, 2024

In recent years, the arrival of summer has been accompanied by record high temperatures. Here's how to stay safe.

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Man pouring water over his head at a fountain in Guadalajara, Mexico
Staying cool is vital during a heat waveImage: Ulises Ruiz/AFP

Sunshine at last! Time to go out to the park or lake and make the most of the nice weather.

But at some point, enough is enough and our bodies need a break. If you spend too much time in the sun, you can get heat exhaustion. And those who work hard in the heat can even suffer heat stroke.

The terms heat exhaustion and heat stroke are often confused. Rather than two distinct things, you can see them more as two different degrees of severity relating to your body getting hotter. How does it happen and how do you recognize both? Here are some tips for a safe summer.

What is heat exhaustion?

A lot of sun or the extreme temperatures of heat waves can make your body overheat and lead to heat exhaustion.

Heat exhaustion is a heat-related illness, like heat rash, heat cramps or heat stroke. Although less severe than heat stroke, if not properly managed it can lead to the more serious variant.

A headache is usually the first sign of heat exhaustion. You are hot, your face is red, you sweat a lot, you move more slowly, and you're likely to experience fatigue, nausea and vomiting. You might also feel dizzy or even faint.

What you might not expect: The skin of someone with heat exhaustion is usually not hot, but rather cool.

Signs of heat exhaustion include: cramps or a heat rash, extreme sweating, getting red in the face, and moving more slowly than normal

Heat exhaustion: What to do?

First of all, those suffering from heat exhaustion should immediately be taken out of the sun, to a cool place or into the shade, and drink water as quickly as possible. Cold, damp cloths can help cool the body. In addition, someone with heat exhaustion should drink plenty of fluids to bring hydration levels back to normal. Cold water or sports drinks replenish lost salts, but avoid alcohol and caffeine. These can dehydrate you even more, on top of excessive sweating, which, according to experts, can cause additional fluid loss of up to two liters on very hot days.

Until the symptoms get better, you need to rest. 

It's important to know that in severe cases, severe vomiting, confusion or even unconsciousness can occur. If that happens, you should see a doctor, if only to rule out heat stroke.

What is heat stroke?

Heat stroke is more dangerous than heat exhaustion and may occur, for example, when you engage in physical activities in a hot environment or when heat exhaustion is not properly treated.

When it's extremely hot outside, the body absorbs more heat than it can release. The body temperature can rise to 41°C (105.8°F) within 10 to 15 minutes. This acute overheating leads to an inflammatory response throughout the body.

The body's temperature regulation system fails and sweat production, for example, stops. Sweating is how your body helps cool itself, so without it your body temperature starts rising.

Heat stroke is life-threatening. Symptoms include impaired consciousness, headache, dizziness and drowsiness; seizures, vomiting, diarrhea and low blood pressure may also occur. Heat stroke develops within one to six hours and can cause death in less than 24 hours unless properly treated.

In the elderly, chronically ill, and children, heat stroke usually occurs because of a combination of high temperatures and severe fluid and electrolyte deficiencies. In healthy adults, too much physical activity in hot sunny weather, such as sports or working outdoors, is what usually causes heat stroke. 

Infographic: Signs of heatstroke

Heat stroke: What to do?

At the first signs of heat stroke, the emergency services should be alerted immediately. The affected person should be taken out of the sun and heat and into a cool or shady place. Their body should be cooled down as quickly as possible with cold water, ice baths or soaked clothes, and the affected person should be given fluids if possible. Excess clothing should be removed.

If unconscious but breathing normally, the person should be placed in a stable horizontal position until emergency personnel arrive. Regular breathing and consciousness must be checked regularly. If the person is not breathing normally, resuscitation efforts must be started.

Avoiding heat exhaustion and heat stroke

In extremely high temperatures, our body's heat regulation system quickly reaches its limits. In addition, older people often drink too little water. As a result, the body cannot produce enough sweat, which makes it difficult for the body to cool down on its own.

In many cases, it is then recommended and safest to call a doctor.

The best way to avoid heat exhaustion or even heat stroke is obvious: Don't get too much sun and especially avoid it around midday; protect your head with a light-colored hat; avoid exposure to extreme heat if possible and drink plenty of fluids. As a rule of thumb, an adult needs at least half a liter of water extra on hot days.

This article was originally published in German