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Heat Exhaustion

Updated: Jul 19, 2025

Heat exhaustion becomes especially common in the summer months. Caused by a variety of things - dehydration, loss of minerals* due to sweating - it can quickly progress to heatstroke if not caught and treated early.


What you might see:

  • Sweating

  • Headache

  • Nausea

  • Dizziness

  • Fainting

  • Irritability

These symptoms worsen as heat exhaustion worsens.


Stretch!

The hypothalamus, a part of the brain, regulates body temperature. If overwhelmed by external heat and dehydration, it struggles to maintain normal function, causing symptoms like dizziness and confusion.


What to do:

  • Get into the shade - out of direct sunlight - as soon as possible.

  • Drink lukewarm water

    • Try to avoid ice-cold water - this is a shock to the body and can worsen symptoms

  • Give the casualty an isotonic drink*

  • If one is not available, adding salt and sugar sachets to a drink functions as an isotonic drink

  • If the casualty's condition worsens, monitor vital signs and be prepared to call an ambulance.


Do not introduce excessive cold to try and "counter" the heat - e.g. do not apply ice packs/cold water/cold shower.


Summary:

Heat exhaustion can be caused by many things, like dehydration and sweating. It can become heatstroke if not treated fast. Symptoms include headache, nausea, and dizziness. You should help them get into the shade immediately, and give them lukewarm water/ an isotonic drink. Don't try to apply ice/give them ice-cold things - this will make it worse.


Glossary:


Minerals: a substance that your body needs to stay healthy.


Isotonic drink: a drink that lets nutrients and minerals get into your body quickly, giving you more energy.


Casualty: the person that is hurt in a first-aid scenario.


For Older Learners

Challenge yourself with these questions!

  1. Why is drinking just plain water sometimes not enough to treat heat exhaustion?

  2. If someone faints from heat exhaustion in a crowded area, how would you distinguish it from other causes of collapse (like a cardiac arrest)?

  3. Imagine you're planning a large outdoor event during summer. What steps would you take to reduce the risk of heat exhaustion among attendees?

Further Information:


Further reading:

 
 
 

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