Heat Exhaustion & Heatstroke: UK Online Doctor Guide
Educational information — not medical advice.
This article was prepared by the OnlineDoctor24 editorial team and reviewed for factual accuracy against UK clinical guidance (NHS and NICE). It is not written by a doctor and does not replace personal medical advice. For symptoms specific to you, book an online doctor consultation.
Key points
- Heat exhaustion is reversible with cooling and fluids.
- Heatstroke (>40°C with confusion) is a medical emergency.
- Acclimatise gradually; hydrate; avoid midday exertion.
- Older adults and children are most vulnerable.
Heat exhaustion
- Heavy sweating.
- Weakness, dizziness.
- Nausea.
- Headache.
- Cool down: shade, fan, cool water sips, wet skin.
Heatstroke (emergency)
- Core temperature >40°C.
- Confusion, slurred speech, seizures.
- Hot dry or sweaty skin.
- Rapid heart and breathing.
- Call emergency services; cool aggressively while waiting.
Prevention
- Hydrate before, during and after activity.
- Acclimatise over 1–2 weeks.
- Avoid alcohol in extreme heat.
- Light loose clothing, wide-brim hat.
- Plan exertion for early morning/evening.
Red flags — when to seek urgent help
Call 999 or go to A&E if you experience any of the following:
- Confusion, fainting or seizure in heat — emergency services
- High fever with hot dry skin
- Vomiting unable to keep fluids down
Frequently asked questions
Common questions UK patients ask about heat illness.
How an online doctor can help
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This article is for general information only and does not replace personal medical advice from a qualified doctor. Content is reviewed against UK NHS and NICE guidance by the OnlineDoctor24 editorial team and is not authored by a medical doctor. If your symptoms worsen or you are unsure, please book a consultation with a GMC-registered GP.
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