If the patient’s stool is black, consider the following reasons: First, consider the patient’s diet of pigmented food and blood products that the body cannot absorb and decompose, such as aconite products, duck blood, pig blood, red heart dragon fruit. Second, consider the upper gastrointestinal bleeding, esophagogastric varices rupture, bleeding or perforation bleeding, ulcer bleeding, when the blood through the gastric acid and the decomposition of various digestive enzymes will cause the stool black. Third, the drug factor, gum as a traditional Chinese medicine, when taken continuously can appear black stool, gastrointestinal drugs bismuth potassium citrate can also lead to black stool, anemia patients taking iron will also lead to black stool, appear black stool, should be as soon as possible to check the stool routine and gastrointestinal endoscopy to identify the cause, in order to facilitate treatment.