Your body knows it needs water, and it’s programmed to conserve fluids to stay hydrated. But drinking alcohol turns down your body’s water-saving signal by reducing the release of a hormone called vasopressin. This antidiuretic hormone (ADH) tells your kidneys to hold on to water. When alcohol lowers ADH, three things happen: -Your kidneys reabsorb less water to send back into your body. -More water stays in your pee, so your bladder fills faster. -The urge to go hits, and you then head to the restroom to empty out. So, even though you’re drinking a liquid, your body may end up with a net loss of water because of the alcohol you’re consuming. Your body typically starts limiting ADH within about 15 minutes of that first sip of alcohol. (It works quickly!) You’ll probably feel the urge to pee soon after that as urine begins to build up in your bladder.