Recognising heat exhaustion and heatstroke and cooling

The body cools itself mainly by sweating. What matters is not the sweat itself but that it evaporates – only then is heat given off from the skin. If the air is very humid, sweat evaporates poorly and just runs off. That is why humid heat is especially stressful, and why fanning helps: it speeds up evaporation.

In heat exhaustion it is mainly the circulation that is overloaded. The body sends a lot of blood to the skin to get rid of heat and at the same time loses fluid through sweat. Less is left for the brain and muscles – hence weakness, dizziness, headache and nausea. If recognised and treated in time, it usually improves quickly.

In heatstroke the body temperature is so high that the brain and organs are damaged. That is why it shows above all in the head: confusion, strange behaviour, staggering, seizures or unconsciousness. The skin can be hot and dry, but also still wet with sweat – so wet skin does not rule out heatstroke. Because the damage increases with every minute, cooling takes priority over waiting for transport.

The most important question is: is the person awake, clear and oriented? Do they know where they are, do they answer sensibly, do they behave as usual? If so, it is more likely heat exhaustion, and you can achieve a lot with shade, rest, cooling and drinking. If their condition does not improve quickly or gets worse, call the emergency number.

With confusion, a change in behaviour, a seizure or unconsciousness, call the emergency number at once and cool continuously until the ambulance crew takes over. Wet the skin with cool water and fan. Place wet cloths or cold packs wrapped in cloth on the neck, armpits and groin – a lot of blood flows close under the skin there, so the cooling reaches the body well. The dispatcher can give you further instructions.

Only alert people who can swallow safely may drink – water or an electrolyte drink in small sips. Anyone who is confused, vomiting or not clearly conscious gets nothing to drink, because they could choke. An unconscious person who is breathing normally goes into the recovery position; you keep cooling and monitor their breathing.

The most common mistake is dismissing confusion as ‘just tired’. Precisely because heatstroke affects thinking, the person affected often does not notice it themselves and may even say they are fine. Trust what you see, and when in doubt, call once too often rather than not at all.

Never leave children, older people or animals in a parked car, not even briefly. A vehicle interior heats up very quickly in the sun, even at temperatures that still feel pleasant outside. A slightly open window makes little difference.

Medication is not part of lay first aid for heat – the treatment is cooling. Immersion up to the neck in cool water is considered very effective for exertional overheating, but only under supervision and with the head kept safely above water; the dispatcher or trained personnel decide on that. And after improving, nobody goes straight back into the heat.

The WHO points out that older people, young children, people with chronic illness and people who work outdoors are particularly at risk from heat. Older people often feel thirst less and sweat less. Small children cannot get themselves out of the heat and do not always say what is wrong.

But young, fit people can also get heatstroke – for example during sport, physical work, hiking in hot regions or at festivals. Here exertion, heat and often too little drinking come together. Anyone who moves a lot produces a great deal of heat themselves.

Homes can also become heat traps, especially top-floor flats during a long heatwave. Then check regularly on older or ill neighbours and relatives. A short call or visit can prevent a lot.

Prevention is easier than treatment. Shift exertion to the cooler times of day, that is, early morning or evening. Take regular breaks in the shade and drink throughout the day, not only when you are very thirsty. Light, pale, airy clothing and a hat also help.

The body gets somewhat used to heat over a few days. Anyone who has just arrived from a cooler climate should therefore take it especially easy in the first days. In a group it is worth looking out for each other: anyone who becomes noticeably slow, seems confused or suddenly stops sweating although it is hot needs a break and attention.

Cooling is simple and possible almost anywhere with water – but only if you recognise in time that it is needed. A first-aid course helps you read the signs with confidence. When in doubt, always call the emergency number and follow the dispatcher's instructions.