If you like beer, and like it in large quantities, this might be a familiar scenario: You sit down at the bar, get a beer and drink it. You drink another one. Maybe a third. Things have gone well up to this point, but now you have to pee. So you go. Once you return to your seat and keep drinking, though, it feels like you’ve crossed a point of no return, and you have to pee again and again.
You’ve "broken the seal." After that initial pee, you seem to have to run to the bathroom every 15 to 20 minutes for the rest of the night, and the urine just won’t stop flowing. What’s going on?
Part of what makes you pee so much while boozing is that alcohol inhibits arginine vasopressin, also known as antidiuretic hormone or ADH. ADH is made in the part of the brain called the hypothalamus, and then stored and released from the pituitary gland at the base of the brain. Its job is to conserve water in the body by reducing its loss in urine. It binds to receptors on the kidneys and promotes water reabsorption, a decrease in the volume of urine sent to the bladder, and excretion of more concentrated urine.
Alcohol throws a wrench into the works, though, and blocks certain nerve channels that help get ADH secreting out into your system. Without ADH carrying on about conserving water, the kidneys don’t reabsorb water as easily and excess water winds up getting dumped into urine to leave the body. With alcohol keeping ADH from doing its job, you produce a lot more water-diluted urine, which fills the bladder quickly and makes you have to pee more often.
So, there’s really no seal to break, no dam to crack open. If anything, the damage was done when you took your first drink and started suppressing your ADH, not when you took your first pee.
But how come you can hold your pee just fine until that first bathroom break, and then it seems you have to go constantly?
First, it takes a little bit of time for alcohol to suppress ADH and for the kidneys to ramp up the water works. When you crack open your first beer, you may have some urine in your bladder already, but also some ADH in your system to keep things from getting out of hand. As you continue to drink, though, your ADH levels drop and your urine production increases. By the time your bladder has filled and you're ready to go to the john, you’ve probably had a few more drinks. Your ADH is more suppressed and your kidneys are working at full tilt, so you’re going to have to go more often.
Additionally, alcoholic beverages can be a bladder irritant for many people and the carbonation of drinks like beer and champagne can cause gas and pressure that contribute to that irritation. As your bladder fills up again after the initial pee, all that irritation can create a very strong urge to pee some more and make your bladder feel fuller than it really is, sending you running to the bathroom over and over again throughout the night.