There are many causes of black excretion, both physiological and pathological. Pathological causes are mainly caused by a small amount of bleeding in the upper gastrointestinal tract, mainly from lesions in the esophagus, stomach, and duodenum, such as gastric ulcers, malignant tumors of the stomach, and esophageal varices in the fundus of the stomach. Physiological causes are mainly caused by diet and drugs. Diet such as various blood products or black-colored food; drugs such as western medicine, iron supplements for anemia, bismuth supplements to protect the gastric mucosa in the treatment of gastric diseases, and taking herbal tonics can also result in black-colored stools. Therefore, the appearance of black feces, you should do stool routine to distinguish physiological or pathological, and then further disposal.