The darkening of stool after taking iron supplements does not necessarily indicate that the drug is taking effect, but may also be the effect of food and digestive tract diseases. To really observe whether iron is absorbed by the body, it is necessary to check the blood routine by drawing blood in order to observe indicators such as hemoglobin, serum iron and ferritin, so as to make a judgment, and the causes of black stools need to be analyzed according to the specific situation. Black stool cause 1, drug factors: oral iron, can be due to the combination of iron and hydrogen sulfide in the intestine and the formation of black iron sulfide, which is manifested as black stool, generally belongs to the normal phenomenon, no special treatment. Non-steroidal anti-inflammatory drugs such as aspirin, as well as anti-platelet drugs such as Prasugrel, can cause gastrointestinal bleeding, which in turn causes black stools and requires prompt medical attention; 2. Food factors: when eating animal offal or animal blood products, which are rich in hemoglobin and iron, they are also able to form iron sulfide in the intestine after consumption, resulting in black stools during defecation, which also usually requires no treatment; 3. Gastrointestinal bleeding: often due to esophagus- Gastric fundic varices, portal hypertension and other diseases that lead to gastrointestinal bleeding, resulting in abdominal pain, bloating, black stools and other symptoms, need to go to the hospital as soon as possible for gastroscopy and other examinations to clarify the cause, and then symptomatic treatment. Analysis of the efficacy of iron supplements When taking iron supplements orally, the efficacy of the drug needs to be analyzed according to the actual condition of the patient. If iron deficiency anemia is the cause, oral iron can usually correct the effect of iron deficiency anemia. If it is due to megaloblastic anemia, it usually does not achieve good results. Precautions When taking iron orally, to avoid blackening of the teeth, choose to use a straw and try to take it during or after a meal to reduce the stimulation of the gastrointestinal tract. When taken together with vitamin C-rich fruits such as apples and oranges, it can also increase the body’s ability to absorb iron. During the oral intake of iron, milk, coffee and strong tea should be avoided to avoid affecting the effect of iron supplementation.