Folic acid is one of the vitamins that can enhance the body’s immunity and promote fetal neurological development. Iron is added to some folic acid medications to help improve the body’s anemia symptoms, and some people will have black stools after taking this type of folic acid. The black color of folic acid stool is mainly due to the fact that iron is not completely absorbed by the body and is discharged with the stool after oxidation in the intestine. The color of the stool will only change, but the nature of the stool will not be abnormal, and it will not be accompanied by abdominal pain, bloating, or diarrhea. For people who have dark stools after taking folic acid, they can stop taking folic acid and it will disappear after metabolizing for a period of time, and if necessary, they can also change to other brands under the guidance of doctors to reduce the symptoms.