Poop that is black and smelly can usually be divided into physiological factors, such as diet and drug effects. Pathological factors are related to gastrointestinal bleeding and blood disease factors. Occasionally a black stool can be observed first; if it occurs several times, you should go to the hospital to determine the cause. I. Physiological factors: 1. Dietary impact: If too much iron-containing food is consumed, such as sheep blood, duck blood, pig blood, pig liver, etc., the iron in animal blood will undergo a chemical reaction in the human intestine to form black iron sulfide, which can lead to black stools. When consuming more ammonia-containing food, can lead to very smelly stool, generally stop eating or taking probiotic-type drugs soon after the symptoms improve, no special treatment; 2, drug effects: patients taking blood iron, activated carbon, bismuth for the treatment of stomach diseases and certain Chinese herbal soup, if taken in excess of a certain dose, can also lead to black stool. Generally do not need to worry, can be relieved after discontinuation. Second, pathological factors: 1, gastrointestinal bleeding: If the patient suffers from peptic ulcer, gastric cancer, gastric mucosal lesions, esophageal varices and other upper gastrointestinal bleeding diseases, upper gastrointestinal bleeding iron in red blood cells, combined with sulfide under the action of intestinal bacteria to form iron sulfide, thus making the stool black. In case of peptic ulcer bleeding, it can be treated with acid suppressants and mucosal protectors. If it is stomach cancer, esophageal varices and other organic lesions, you need to seek medical attention, endoscopic treatment and surgery if necessary; 2, blood diseases: blood system diseases such as hemophilia, leukemia, etc., such as the involvement of the digestive tract, will also lead to black stools. You can take tranexamic acid tablets, hemostatic minerals, vitamin K2 and other drugs for treatment.