Simple H. pylori infection usually does not show black stool, taking bismuth in the eradication of H. pylori will show black stool, and the color of stool will turn to normal 1~2 days after stopping the medication. The standard treatment for H. pylori in China uses a quadruple drug regimen taken on time for 14 days, and the drugs include one proton pump inhibitor (e.g., omeprazole, rabeprazole, etc.), two antibiotics (e.g., amoxicillin, metronidazole, levofloxacin, furazolidone, etc.), and one bismuth agent (e.g., bismuth potassium citrate, colloidal bismuth in pectin, etc.). Among them, the administration of bismuth agent will lead to the production of black stools. Generally, after stopping the medication, the residual bismuth agent components are cleared through the body’s metabolism for 1~2 days, and the color of the feces can be turned to normal. If black stool occurs without taking bismuth or still exists after stopping bismuth, it is necessary to go to the hospital to do fecal occult blood and other tests to clarify the cause of the black stool, and to be alert to the presence of gastrointestinal bleeding and other diseases, to avoid delaying the condition.