Blood in the stool after drinking beer may be due to anorectal diseases such as hemorrhoids or anal fissure, or it may be caused by diseases such as gastrointestinal bleeding. 1. Anal and intestinal diseases: after drinking beer, due to alcohol can promote capillary expansion, if it itself suffers from hemorrhoids or anal fissure and other diseases, under the stimulation of alcohol, the intestinal absorption ability to strengthen the fecal matter is more dry, defecation to stimulate the anus, this time defecation will aggravate hemorrhoids and anal fissure bleeding symptoms, resulting in blood in the stool. 2. Gastrointestinal bleeding: because alcohol can stimulate the gastrointestinal mucosa, so if you have gastric ulcer or duodenal ulcer and other diseases, drink the beer to stimulate the mucosa, resulting in capillary rupture, there will be gastrointestinal bleeding, blood from the gastrointestinal tract, blood in the stool symptoms. Blood in the stool after drinking beer, there may also be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.