Dark stools are tarry stools that are black or brownish-black in color. Black stools are usually caused by dietary factors, medications, and gastrointestinal bleeding. It can be treated by adjusting diet, stopping iron medication and taking oral omeprazole enteric-coated capsules. 1. Dietary factors: black stools may occur due to recent consumption of animal blood products such as pig’s blood, duck’s blood, chicken’s blood and so on. Patients can adjust their diet and the black stools will improve naturally. 2. Drug factor: When taking iron containing drugs (such as ferrous fumarate), the iron itself is black, and when not fully absorbed, it will be discharged with the stool, resulting in black stools. Stop using these drugs in time, the black stool will be improved. 3. Gastrointestinal bleeding: If the blood stays in the intestines for a long time due to gastroduodenal ulcers, reflux esophagitis and other causes of gastrointestinal bleeding, the iron in hemoglobin combines with intestinal sulfur to produce ferrous sulfide, which will lead to black stools. It can be treated by oral omeprazole enteric-coated capsules, aluminum phosphate gel and other drugs as prescribed by the doctor. After the exclusion of dietary and medication factors, black stools should be consulted in a timely manner in order to clarify the cause of the disease and correct treatment, and medications should be used under the guidance of a doctor.