General oral iron supplement drugs are ferrous, it will be converted into trivalent iron in the body, the final metabolism will be discharged outside the body into iron porphyrin, after oxidation after the black, so the iron supplement drugs, if the oral iron supplement drugs, the general black stools is normal, do not need to stop the drug. But there are some gastrointestinal bleeding, because the stool will also be black, so it is best to test the stool, clear occult blood there is no red blood cells in the stool, if the occult blood is negative, it will be more assured. If the occult blood is positive, we should consider the possibility of gastrointestinal bleeding, we need to carry out symptomatic treatment for gastrointestinal bleeding, but most of the oral iron supplementation, the stool will be black, intravenous iron supplementation generally will not have an effect. The majority of oral iron supplementation, the stool will be black, intravenous iron supplementation does not usually have an impact.