Dark and sticky stools may be caused by diet, medication, gastrointestinal bleeding and other reasons. 1. Diet: If you ingest blood products such as pig’s blood, duck’s blood, etc., it can cause darker and thicker stools. 2. Medications: If you take iron, bismuth and other medications, such as ferrous succinate and bismuth potassium citrate, you can also experience side effects such as darkened stools, which may be darker and more viscous. 3. Gastrointestinal bleeding: such as gastrointestinal ulcers and other mucosal capillary rupture bleeding, hemoglobin in the iron and gastrointestinal tract sulfide interactions, may appear in the stool black more viscous situation. It is recommended that people with dark and sticky stools go to the hospital in time to clarify the cause, and if treatment is needed, standardized treatment should be carried out under the guidance of a doctor to avoid delaying the condition.