Black stools with no other symptoms may be the result of recent consumption of blood products or taking iron-containing agents, or there may be mild gastrointestinal bleeding. Having black stools is not necessarily a sign of illness. Black stools can also occur if you have consumed foods high in iron, such as blood products and spinach, or if you have recently taken iron-containing agents, such as ferrous succinate, and usually have no other symptoms. If gastrointestinal bleeding is present, the blood also contains a lot of iron, and the blood enters the intestines, where it can also produce ferrous sulfide in the mechanism described above, and black stools appear. If the amount of bleeding is reduced, there may be only black stools and no other symptoms. The appearance of black stool can go to the gastroenterology department to improve the examination, clear diagnosis and standardized treatment.