Black stools sticking to the toilet may be related to diet, medications, and gastrointestinal bleeding. 1. Diet or medication: The appearance of black stools sticking to the toilet may be related to taking medications containing iron or bismuth, or eating animal blood products. Simply black stool, no other abnormal clinical manifestations, fecal occult blood test is negative. If it is caused by taking drugs such as iron and bismuth, black stools may persist. If it is caused by food, it can be relieved by itself. 2. Gastrointestinal bleeding: If the stool is black and tarry, you should be highly alert to the possibility of gastrointestinal bleeding. It is common in lower gastrointestinal bleeding, such as infectious enteritis, non-infectious enteritis, ischemic bowel disease and so on. Examination of gastroenteroscopy may show abnormalities, fecal routine with occult blood. The appearance of black stools indicates that the amount of bleeding reaches more than 50 ml. Black stool sticking to the toilet, it is recommended to consult a doctor in time to clarify the cause of black stool, if it is caused by disease, it needs to be treated in time to avoid delaying the condition.