The reason for the black stool of bismuth pectin is mainly because bismuth pectin is eventually decomposed under the action of digestive juices, and the black metabolites are eliminated from the body with the stool to form black stool, which is a normal drug reaction. Clinical common such as ferrous sulfate treatment of anemia, will also cause black stool, is also a normal drug reaction. When taking bismuth pectin, black stools should be alert to the presence of organic lesions of the gastrointestinal tract, such as erosive gastritis, gastric ulcer, duodenal ulcer, or even gastric cancer. The easiest way to check is to improve the fecal occult blood test, if the occult blood is positive, it is considered to have gastrointestinal organic lesions. The most reliable is to improve the gastrointestinal tract of gastroscopy and enteroscopy, in order to ultimately clarify the cause, so in taking pectin bismuth stool black, must pay attention to identify.