You don't need to be a scientist to see the toilet queues on a Saturday night, or at an event, to make the link between drinking alcohol and the need to pee. So why exactly does drinking alcohol make us need to pee more than when we drink soft drinks or water?

The science of why alcohol makes you pee more

“Alcohol is a diuretic,” says Professor Oliver James, Head of Clinical Medical Sciences at Newcastle University. “It acts on the kidneys to make you pee out much more than you take in – which is why you need to go to the toilet so often when you drink.” In fact for every 1g of alcohol drunk, urine excretion increases by 10ml1.

Alcohol also reduces the production of a hormone called vasopressin, which tells your kidneys to reabsorb water rather than flush it out through the bladder. With the body's natural signal switched off, the bladder is free to fill up with fluid.

Find out if you're drinking too much with our Self Assessment tool.

Dashes to the toilet

A common side effect of drinking is needing the toilet just five minutes after your last visit. This irritating experience (usually known as 'breaking the seal') happens because alcohol delivers a hefty double whammy to your kidneys.

"Suppose you have a pint at lunchtime," explains Oliver. "At some point you'll need to go to the toilet and get rid of the pint of liquid you've just drunk. Then, an hour later, you'll have to pee again because of the added diuretic effect."

Find time for water when drinking alcohol

With fluid leaving your body so quickly, dehydration can be a big problem. Though it might seem like even more liquid is the last thing you need when you’re having to dash to the gents/ladies, regular sips of water during and after drinking are what you need to keep yourself hydrated.

Another way to avoid dehydration from alcohol is to stay within the UK Chief Medical Officers' (CMO) low risk drinking guidelines which advises:

  • To keep health risks from alcohol to a low level it is safest not to drink more than 14 units a week on a regular basis. 
  • If you regularly drink as much as 14 units per week, it's best to spread your drinking evenly over three or more days. If you have one or two heavy drinking episodes a week, you increase your risk of death from long-term illness and injuries. 
  • The risk of developing a range of health problems (including cancers of the mouth, throat and breast) increases the more you drink on a regular basis. 
  • If you wish to cut down the amount you drink, a good way to help achieve this is to have several drink-free days a week.

Use our Unit and calorie Calculator to see how many units are in your drinks.

Alcoholic drinks with less volume won’t stop the need to pee!

Switching to alcoholic drinks with less volume, such as shots, won't stem the flow either. That’s because whether you're drinking pints or doing shots, it's the diuretic element of the alcohol which is key to producing all that wee.

Does weeing all the alcohol out of my system help prevent a hangover?

Unfortunately not.  Because alcohol promotes peeing, it can lead to dehydration, which causes the nausea and headache associated with bad hangovers. It's also why your mouth might feel like the driest place on earth the next day.

Want to learn more about what a hangover is?

 

References

(1) Eggleton MG, ‘The diuretic action of alcohol in man’,J Physiol 1942, vol.101, pp.172-191. Available at:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1393383/

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