Dark brown stool is not normal, dark brown stool, consider dietary factors, drug factors and upper gastrointestinal bleeding, etc., as follows: First, dietary factors: eating a lot of greasy and high protein food, slow emptying of the stool, will appear dark brown. There is also the consumption of animal blood, animal offal, etc., will appear black or dark brown stool. Second, drug factors: such as taking drugs containing iron, bismuth, will make the stool appear black or dark brown. Third, gastrointestinal bleeding: Adults with this disease bleed >5mL per day, the fecal occult blood test is positive, and the naked eye view is still yellow stool. If the amount of bleeding is >50mL, black or tarry stools may appear. The dark brown color of stool is considered to increase the amount of bleeding. Clinically, there are many causes of gastrointestinal bleeding, the most common being peptic ulcer, ruptured esophagogastric varices, acute erosive hemorrhagic gastritis, and gastric cancer. When a change in stool color occurs, seek immediate medical attention. If a clear diagnosis of gastrointestinal bleeding is made, it is important to immediately identify the cause of bleeding, assess the amount of bleeding, understand the site of bleeding, and give precise diagnosis and treatment under the guidance of a doctor to avoid delaying the condition.