Why does alcohol make you pee more?

The science of why alcohol makes you pee more

Alcohol is a diuretic, which means it promotes water loss through urine.¹ It does this by inhibiting the production of a hormone called vasopressin, which plays a large role in the regulation of water excretion. 

When it’s working correctly, vasopressin tells your kidneys to reabsorb water if it’s needed by your body, rather than flush it out through the bladder. But the way alcohol interferes with this natural signal, switching it off, means the bladder is free to fill up with urine which the end result being you need to pee more often.² 

Frequent trips to the toilet

The consequence is that we lose more liquid through our pee than we take in. That’s why we need to go to the toilet more often when we drink alcohol and also why we’re at danger of becoming dehydrated unless we replace the excess lost fluid by drinking more water. 

Getting up to go to the toilet at night can disrupt your sleep too. And that’s on top of the effect alcohol has in disrupting the restorative REM stage of sleep,³ so cutting back on alcohol – especially before bed – can mean you wake up feeling fresher. 

Alcohol and sleep 

Alcohol and dehydration

Alcohol makes us pee more and more frequently, and fluid leaving our bodies at this rate can lead to dehydration if not replaced. It is important to replace lost fluid by drinking water if we choose to drink alcohol. 

Dehydration is more likely in hot weather even without drinking alcohol, so all this is especially important if you are drinking when the weather is hot. Heatwaves can be dangerous in their own right – and adding alcohol to the mix increases your risk of dehydration, heat exhaustion or heat stroke.⁴ 

Dehydration can become serious and lead to confusion and seizures. Serious dehydration requires urgent medical attention.⁵ 

The effects of dehydration include feeling thirsty, dizzy, lightheaded and tired, experiencing a dry mouth and lips and dark yellow and strong-smelling pee. 

Dehydration makes hangover symptoms worse too.⁶ It’s important to replace lost fluid by drinking extra water if you choose to drink alcohol.  

How to avoid a hangover

Limiting the impact of the diuretic effect of alcohol

The only way to avoid the diuretic effect of alcohol is not to drink any at all. So to avoid having to pee so frequently, limit the amount of alcohol you drink. And to avoid becoming dehydrated, make sure you replace lost fluids with water. 

To keep risks from alcohol low, stick to the UK Chief Medical Officers' low risk drinking guidelines of no more than 14 units a week, taking several drink-free days every week and never binge drinking. 

Think you might be drinking too much? Take our free alcohol quiz