The unpleasant digestive aftermath of a heavy night of drinking has long been joked about in social conversations, but medical professionals say there is a genuine biological explanation behind the embarrassing phenomenon many people refer to as “booze butt.” Doctors describe it as a sudden digestive reaction that can leave people rushing to the bathroom the morning after consuming alcohol. While it may sound humorous, the experience is rooted in the way alcohol affects the body’s gastrointestinal system. Alcohol is known to irritate the lining of the stomach and intestines, disrupting the delicate processes that control digestion and fluid balance.

When people drink heavily during a night out, the digestive system can become overwhelmed by the chemical effects of alcohol as well as by the additional factors that often accompany drinking, such as late-night meals, sugary mixers, and dehydration. By the time the body begins processing everything hours later, the digestive tract may respond by speeding up the movement of food and liquid through the intestines. This rapid movement can reduce the amount of water absorbed by the colon, resulting in loose stools or sudden diarrhea.