The science of why alcohol makes you pee more
Alcohol is a diuretic, which means it promotes water loss through urine. It does this by inhibiting the production of a hormone called vasopressin, which plays a large role in the regulation of water excretion.
Vasopressin tells your kidneys to reabsorb water rather than flush it out through the bladder if it is needed by the body. With the body's natural signal switched off, the bladder is free to fill up with urine which is then excreted when we go to the toilet.1
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.
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.
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 can become serious and lead to confusion and seizures. Serious dehydration requires urgent medical attention.2
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.
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 and taking several drink-free days every week.