The common causes of black stools are chronic enteritis, dyspepsia, upper gastrointestinal bleeding, food and drug factors, and other causes, please go to the hospital in time to clarify the cause of the disease. 1. Chronic enteritis: chronic intestinal inflammatory diseases, because of bacterial, viral infections or allergies, allergic reactions and other causes, clinical manifestations of chronic recurrent abdominal pain, diarrhea, black stools and other symptoms, resulting in gastrointestinal dysfunction. 2. Dyspepsia: It is a disease caused by gastric dysfunction, with abdominal pain as the main symptom, mostly irregular, manifested as fullness and pain, relieved after eating, unshaped stools, black stools and other color changes. 3. Upper gastrointestinal bleeding: when the human digestive tract bleeds, the iron in the hemoglobin in the red blood cells and sulfide combine to form iron sulfide, and defecation discharges the iron sulfide out of the body, resulting in tarry black stools, sticky texture. 4. Food and drug factors: eating too much pig’s blood, chicken blood, etc. or taking iron-containing foods, these foods and drugs are rich in iron and sulfide combination, black stools, the body does not fully digest the food, resulting in unshaped stools. There are other factors that may contribute to the dark and sparse unshapely stool, you should go to the hospital outpatient clinic in time to clarify the cause of the disease, under the guidance of a professional physician, follow the doctor’s instructions for treatment, do not self-medication to avoid delaying the condition.