The black color of stool after taking iron supplements is mostly a normal phenomenon, and it is not possible to judge the absorption effect of iron supplements from this, and the effect of iron supplementation can be judged by regular blood tests in the hospital. After oral iron supplements, iron is usually not completely absorbed by the body, some of which can be combined with hydrogen sulfide in the intestine, resulting in the formation of black iron sulfide, so that the color of the stool is black. However, part of the population iron absorption is poor, or too much iron dose caused by incomplete absorption, can also be manifested as black stool color, so we can not judge the effect of iron absorption. Commonly used oral iron supplements are ferrous sulfate, ferrous protein succinate, etc., patients with iron deficiency anemia should be taken under the guidance of a physician. For the use of iron treatment caused by black stool, usually do not need to do any special treatment, after stopping the use of drugs, stool color can gradually return to normal.