Coffee contains caffeine, long-term excessive coffee drinking may cause irritable bowel syndrome, ulcerative colitis, indigestion and other diseases. 1. Irritable bowel syndrome: Caffeine may stimulate the intestinal mucosa, leading to intestinal spasms, accelerated peristalsis, causing reduced absorption and leading to diarrhea. 2. Ulcerative colitis: drinking coffee in excess for a long period of time can be irritating to the colonic mucosa. If you drink coffee in excess for a long time may damage the colon mucosa and induce ulcerative colitis, which may lead to diarrhea, vomiting and other symptoms. 3. Indigestion: Long-term overdrinking of coffee may lead to intestinal flora imbalance, which in turn leads to indigestion due to intestinal flora imbalance such as bloating, diarrhea and other symptoms. Daily should drink coffee in moderation, excessive coffee on the adverse effects of gastrointestinal, for gastrointestinal function is not good for the crowd, it is recommended not to drink coffee, if abdominal pain, diarrhea, bloating, vomiting and other symptoms, the need to consult a doctor in a timely manner, under the guidance of the doctor for standardized treatment.