It is normal for iron-containing foods or medications to be reduced to ferrous sulfate in the intestinal tract, which in turn causes dark stools. Therefore, it is normal for patients who take oral iron supplements, such as iron polysaccharide complexes, multivitamin complexes, etc., to have dark stools, but they need to be differentiated from gastrointestinal bleeding. If a patient has black stools due to gastrointestinal bleeding, there are usually abdominal symptoms, such as epigastric pain, acid reflux, heartburn, nausea, vomiting, and even vomiting of blood. Therefore, if a patient has a clear history of oral iron intake and has dark stools, there is no need to be overly anxious, but if the dark stools are accompanied by obvious abdominal symptoms, it is recommended that the patient should go to the hospital for consultation.