The cause of black stool is divided into physiological and pathological, caused by physiological factors do not require special treatment, while pathological factors caused by black stool should be actively treated for the original disease. A, physiological 1, food: if the patient eats darker food, such as duck blood, chicken blood, sheep blood, pig blood, animal liver, etc. may appear black stool, generally reduce the intake of such food, stool color will gradually return to normal; 2, drugs: drugs cause black stool mainly oral certain herbs, such as angelica, he shou wu, reed, etc., as well as iron, bismuth and biochar, etc., can also cause black stool. Usually the color of the stool can return to normal after stopping the drug; 3, other: if the patient has nosebleeds, tooth extraction, tonsillectomy and other operations in recent days, the blood swallowed may also lead to black stool. At this time, pay attention to rest, take anti-inflammatory drugs and hemostatic drugs as prescribed, rest for a period of time after the operation, to stop bleeding black stool symptoms can gradually disappear. Second, pathological The pathological cause of black stool is mainly gastrointestinal bleeding, such as peptic ulcer, esophagogastric fundic varices, gastric cancer, gastrointestinal polyps, blood diseases, uremia and other causes of gastric, esophageal and duodenal bleeding, can cause black stool, small intestine and colon lesions can also cause black stool. Therefore, patients who do not have the above related food as well as drug history, if they have black stool that cannot be relieved and usually have abdominal pain, diarrhea or dizziness and other abnormal manifestations, it is recommended to consult a doctor promptly to clarify the related etiology, and to treat the primary disease, such as surgical removal of tumors and polyps, while stopping the bleeding with drugs and endoscopy.