Dark stools, but normal gastrointestinal function, consider and dietary factors, taking certain drugs, can also be considered related to gastrointestinal bleeding. 1. Dietary factors: short-term black stool color, the patient does not have any discomfort symptoms, consider and dietary factors. Such as the recent intake of more blood products, such as chicken blood, duck blood, pig blood, sheep blood and animal liver. Blood products are oxidized in the intestinal tract, which may lead to black stool color. 2. Drugs: Taking certain drugs during the black color of the stool, consider and drug-related. Taking drugs for iron deficiency anemia, such as ferrous sulfate; taking bismuth drugs, such as bismuth potassium citrate, colloidal bismuth pectin, can also lead to black stool color. 3. Digestive bleeding: Problems in the digestive system, such as colon tumors, gastrointestinal vascular malformations, intestinal inflammation and other diseases lead to local bleeding, which is also the main cause of black stool color. The black color of stool caused by diet, medication and other factors usually does not require special treatment, and the patient’s condition can be improved by stopping suspicious food and medication. If digestive diseases are suspected, it is recommended to go to the gastroenterology department of the hospital for gastroenteroscopy and treatment in time.