Heatstroke vs heat exhaustion: Signs, symptoms and how to prevent both

Woman in hot weather with heatstroke. (Getty Images)
Preventing heatstroke during hot weather is key. (Getty Images)

Summer brings warmer temperatures and chances of heatwaves, which is why it's more important now than ever to know the signs and symptoms of heatstroke and how it differs to heat exhaustion to prevent both from happening.

The Met Office has confirmed that several parts of the UK experienced a heatwave in early June, with temperatures reaching 32.2C in Surrey.

While many of us might be tempted to sun ourselves on the beach, in a beer garden or our local park, we're far from used to extreme temperatures in the UK - such as the 40C day we saw in 2022 - and taking measures to stay safe is the main priority, whether we're fit and healthy or not.

Young people enjoying drinks during happy hour at terrace bar toasting with beers and chatting. (Getty Images)
Al fresco drinking can increase the risk of heatstroke. (Getty Images)

What is heatstroke?

"Heatstroke occurs when you have been exposed to a hot temperature for a prolonged period of time," Dr Sonal Shah, NHS GP and lifestyle medicine expert, previously explained to Yahoo Life UK.

Heat exhaustion will likely strike first, but if you ignore the signs you could be on a one-way ticket to heatstroke and that’s not somewhere you want to be.

Heatstroke signs and symptoms

  • Headaches, dizziness or light-headedness

  • Skin may be red, inflamed or have small bumps on it

  • Muscle cramps, nausea, vomiting and even palpitations are other reported symptoms

Dr Shah said that in some cases people develop a mild temperature, of around 38C. "We call this heat exhaustion," she said. "If people experience any of these symptoms they should move away from the sun to a shaded area and efforts should be made to cool them down either with fans or even a cool shower. Give them plenty to drink to help rehydrate them."

Though in most cases symptoms will improve within half an hour, if people remain exposed to high temperatures they may experience heatstroke, a dangerous condition that needs urgent treatment.

"With heatstroke people may appear agitated, confused, have seizures, or even become unconscious and immediate emergency help should be sought," Dr Shah warned.

Who is most at risk of heatstroke?

According to Dr Shah, the vulnerable list includes young people and babies, elderly people or those with chronic conditions.

"In the hot weather it may also be worth checking on elderly neighbours or relatives to ensure they are not unwell due to the weather," she added, echoing official advice.

However, when very hot, everyone needs to be extra cautious.

Woman sitting in the shade. (Getty Images)
Avoid sitting in in the sunshine when the temperatures are highest, and stay in the shade if you do go outsidside. (Getty Images)

What can you do to prevent heatstroke?

"Avoid getting heatstroke by not sitting in the direct sun between 11-3 when the sun is at its hottest, make efforts to stay cool, drinking well and avoiding too many sugary or alcoholic drinks as these have dehydrating effects," advised Dr Shah.

On a normal day people need around 1.5 to 2 litres of water day, which is about eight to 10 glasses. But, in hot weather, you can become dehydrated quicker, so drink more often and aim for at least two litres.

The top ways for staying safe in the heat, as listed by the Met Office, are to:

  • Look out for those who may struggle to keep themselves cool and hydrated. Older people, those with underlying conditions and those who live alone are particularly at risk

  • If you live alone, ask a relative or friend to phone to check that you are not having difficulties during periods of extreme heat

  • Stay cool indoors: Close curtains on rooms that face the sun to keep indoor spaces cooler and remember it may be cooler outdoors than indoors

  • If going outdoors, use cool spaces considerately

  • Drink plenty of fluids and avoid excess alcohol

  • Never leave anyone in a closed, parked vehicle, especially infants, young children or animals

  • Try to keep out of the sun between 11am to 3pm, when the UV rays are strongest

  • Walk in the shade, apply sunscreen and wear a wide-brimmed hat, if you have to go out in the heat

  • Avoid physical exertion in the hottest parts of the day

  • Make sure you take water with you, if you are travelling

  • Check the latest weather forecast and temperature warnings – you can find these on TV, radio, mobile app or website

  • During warm weather going for a swim can provide much welcomed relief. If you are going into open water to cool down, take care and follow local safety advice

Some further tips for people to avoid heatstroke, as listed by the NHS, are to:

  • take cool baths or showers

  • wear light-coloured, loose clothing

  • sprinkle water over skin or clothes

  • avoid extreme exercise

Man drinking water after suffering from heat exhaustion. (Getty Images)
If you feel like you might be starting to suffer from heat exhaustion move out of the sun and drink plenty of fluids. (Getty Images)

How is heat exhaustion treated?

The NHS advises following four steps:

  1. Move them to a cool place

  2. Get them to lie down and raise their feet slightly

  3. Get them to drink plenty of water (sports or rehydration drinks are OK)

  4. Cool their skin – spray or sponge them with cool water and fan them (cold packs around the armpits or neck are good, to)

Stay with them until they're better. They should start to cool down and feel better within 30 minutes.

However, if you suspect someone is suffering from heatstroke, you should seek emergency help immediately.

Call 999 if you or someone else have any of these signs:

  • feeling unwell after 30 minutes of resting in a cool place and drinking plenty of water

  • not sweating even while feeling too hot

  • a high temperature of 40C or above

  • fast breathing or shortness of breath

  • feeling confused

  • a fit (seizure)

  • loss of consciousness

  • not responsive

Put the person in the recovery position if they lose consciousness while you're waiting for help.

For more information visit the the NHS' page on heatwaves and how to cope in hot weather.

Watch: Top tips for protecting your skin in the sun