Why does alcohol make us pee so much? – The science behind ‘breaking the seal’

Why is it that on every night out, I spend half the night queueing for the loo? And before that I face the inner turmoil of ‘do I go or hold it in?’ to avoid ‘breaking the seal’, because apparently when you let yourself pee once the floodgates are open and you just can’t stop needing to go. I just had to find out why alcohol has this effect on us, and if the ‘breaking the seal’ is a real thing.

breaking the seal
Alcohol making you pee so much is particularly an issue at a festival with horrible porta-loos that you queue 20 mins for the privilege of using…

Why does alcohol make us need to pee so much?

Drinking makes us need to go so often because it is a diuretic (that’s a fancy word for ‘substance that makes you need to wee a lot’). It has this effect by acting on the pituitary gland, reducing the amount of anti-diuretic hormone (aka Vasopressin) the pituitary gland releases. Normally anti-diuretic hormone would act on the kidneys and make them reabsorb water, so there is less volume of water in your urine – making you produce less pee. But when alcohol reduces the amount of anti-diuretic hormone, the excess water is not reabsorbed by the kidneys, and all that extra liquid ends up increasing the amount of urine we produce when we drink. 

By the way – when we are drunk, so much water gets flushed out of our body that our liver has to grab water from other organs to be able to deal with all the toxins we give it on a night out. This includes water being drawn from the brain, which gives us that all too familiar headache the next day.

Does switching to shots help?

Some friends think that switching from pints or other long drinks to shots will make the need to pee less because the volume of liquid is less. These friends are wrong – the diuretic effect is still just as bad with shots because it’s the alcohol that makes you go more, not the increased volume of liquid you are taking in. 

Does ‘breaking the seal’ make it worse?

As I said before, we all tend to hold it in until we are about to burst because of a common conception that the diuretic effect of alcohol works in a ‘once you pop you just can’t stop’ kind of way, in that once we have that first wee, we then won’t be able to stop. There is actually no evidence for this. It is a lie. What actually happens is that by the time you let yourself pee, enough time would have passed for the diuretic effect of alcohol to kick in. Its has nothing to do with when you decide to go / how long you wait – so just do everyone a favour and next time you drink stop squirming and just go and pee! 

So I have once again cleared up one of life’s great mysteries using science, you may thank me Friday night with a glass of champagne (you will probably find me in the line for the loo…)

Till next time,




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