It is possible that drinking red wine causes gastrointestinal bleeding can lead to black stools. It is mostly seen in patients with peptic ulcers, blood diseases, digestive tract tumors and other diseases. 1. Peptic ulcers: for example, gastric ulcers, duodenal ulcers, esophageal ulcers, stress ulcers, etc. Drinking red wine to stimulate the ulcer surface may cause bleeding leading to black stools. 2. Blood diseases: for example, thrombocytopenic purpura can cause bleeding, if you happen to drink red wine can also lead to bleeding stools are black. 3. Tumors of the digestive tract, such as stomach cancer, esophageal cancer, etc., may cause bleeding in the digestive tract and lead to black stools if you happen to drink red wine. Patients who drink red wine and have black stools should actively seek medical treatment, and patients should not use medication on their own to avoid adverse results, but should follow standardized treatment under the guidance of physician’s consultation.