The situation of black stool after taking drugs for H. pylori is mainly related to the inclusion of bismuth in the drugs commonly used for the treatment of H. pylori, bismuth potassium citrate and bismuth pectin. During the medication period, certain adverse reactions may be shown, including the ammonia taste that may remain in the mouth after taking the medication, the black color of the tongue and stool, etc. Generally, the symptoms will disappear on their own after stopping the medication and will not have long-term effects on the body. A small number of patients may also experience varying degrees of nausea and constipation, but there is generally no need to worry too much if you take the medication regularly. If you accidentally overdose or experience other serious adverse reactions, it is recommended to seek medical attention immediately. If black stool still appears after stopping the medicine for a period of time, diseases of the digestive tract itself can be considered, such as bleeding from ruptured esophageal and fundic varices, ulcers and inflammation of the stomach and intestinal tract, parasitic infections, hemorrhoids, intestinal overlap, anal fissure, etc. In addition, other systemic diseases outside the digestive tract, such as blood diseases, acute infectious diseases, vitamin deficiency, poisoning or toxic effects of drugs, etc. can also cause black stool. Since black stools caused by bismuth are easily confused with black stools caused by other diseases, it is also recommended to seek immediate medical attention if black stools persist even after stopping the medication. In addition, eating foods containing large amounts of iron such as pig’s blood and duck’s blood can also lead to black stools, which is a normal physiological phenomenon and not a cause for concern.