Alcohol in a heatwave

Alcohol dehydrates you – so it’s important to stay safe if you are planning to drink during hot weather.

Heatwaves can be dangerous in their own right – and adding alcohol to the mix increases your risk of dehydration, heat exhaustion, or heat stroke.^1,2,3

If you do decide to drink alcohol during especially hot weather, there are things you can do to keep yourself safe. Read our quick guide.

Heatwaves can affect anyone but some people are more vulnerable than others including people who are dependent on alcohol, people with diabetes, kidney disease, Parkinson’s disease, some mental health conditions, and older people (especially those over 75).⁴

Drink plenty of water

Alcohol is a diuretic, which means it encourages the kidneys to get rid of fluid.⁵ That’s why you tend to urinate (pee) much more when you drink alcohol.

Alcohol also makes you sweat more because it interferes with your body’s ability to control its own temperature.^6,7 Combined with the fact that alcohol makes you pee more,⁸ you can lose more fluid than you take in and become dehydrated unless you replace that lost fluid by drinking extra water.

Limit the amount of alcohol you drink and drink plenty of water or soft drinks in between alcoholic drinks to prevent dehydration.

During a heatwave, this advice is even more important. So, as well as sticking to the Chief Medical Officers' low risk drinking guidelines, make sure you drink plenty of water to reduce the risk of dehydration, heat exhaustion, or heat stroke.

Dehydration can cause headaches, dizziness, sickness, and tiredness. Serious dehydration requires urgent medical attention – it can cause confusion and for you to become disorientated.⁹

Don’t drink and swim

While going for a swim may seem like a good idea to cool off on a hot day, don’t swim if you’ve been drinking any alcohol.

Alcohol consumption is known to increase drowning risk.¹⁰

Drinking alcohol impairs your judgement, balance, and coordination – seriously affecting your ability to get yourself out of trouble and making swimming very difficult.¹¹

National drowning data from Royal Life Saving Society (RLSS) says around a quarter (26%) of accidental fatalities in 2022, were under the influence of drugs and/ or alcohol.¹² Among people aged 18-25 who lost their lives to accidental drowning, almost half (46%) had alcohol and/ or drugs in their bloodstream. Many of them drowned because they walked home alone and fell into the water.¹³

The RLSS have a dedicated Don’t Drink and Drown campaign that aims to reduce the high number of university students who drown after drinking.

Keep it low risk

Whatever the weather, it’s important to stick to the UK Chief Medical Officers’ (CMOs’) low risk drinking guidelines. That means – for both men and women – drinking no more than 14 units a week, spread over three or more days with several drink-free days, and no bingeing.¹⁴

Summer evenings are longer, so if you are drinking it’s a good idea to keep track of how much alcohol you’re having to make sure you’re sticking to the guidelines.

Binge drinking – having a lot of alcohol in a short space of time – can be extremely dangerous.¹⁵ It takes roughly one hour for an average adult to process one unit of alcohol. This means that within an hour there should be, in theory, little or no alcohol left in the blood of an adult, although this varies from person to person.¹⁶

Drinking alcohol can affect your judgment too.¹⁷ So you may not recognise early warning signs of heat exhaustion or sunburn.

Go alcohol-free, or low alcohol

Swapping a standard strength beer, wine, or spirit for a low alcohol or alcohol-free alternative could help you cut your drinking – and you will be joining a growing number of people. Figures from 2025 show 45% of UK drinkers consumed low or alcohol-free drinks in the last 12 months, up from 22% in 2021; and three in five (61%) use these as a replacement for alcoholic drinks.¹⁸

If you’re looking for a way to cut down on alcohol without cutting it out completely, alcohol-free or low alcohol drinks could be right for you – and you’ll be less likely to get dehydrated during hot weather.¹⁹

Low alcohol drinks contain up to 1.2% alcohol by volume (ABV). Alcohol-free drinks contain up to 0.5% ABV, with many following government guidance in England to contain 0.05% ABV or less.²⁰

Swap to an alcohol-free cocktail

If you’re thinking of having a cocktail, it’s important to know how many units of alcohol are in your drink – otherwise you could end up drinking more than you intended. You can check how many units are in your drinks with our Unit and Calorie Calculator below.

A good alternative, if you fancy a mixed drink, is to go for an alcohol-free cocktail instead. Many bars and restaurants now sell a range of ‘virgin’ or alcohol-free drinks – including a growing number of alcohol-free bars. Or check out some recipes via the link below for some easy alcohol-free cocktails you can try at home.

For anyone watching their waistline, it’s worth knowing cocktails and alcohol-free cocktails can be high in sugar, making it easy to consume a lot of calories without realising it. Try alternating with low calorie soft drinks or still or sparkling water to help you cut down the calories – and consider swapping sugary syrups for low calorie alternatives.

If you’re making alcoholic drinks at home, you can use an alcohol unit measuring cup to avoid over-pouring. And if you are out, the bartender can advise on what measure of drink you’ve ordered.

Alcohol-free cocktails made easy