Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. There can be various reasons for black stool as - bleeding ulcer - inflammatory bowel condition as IBS or others - hemorrhoids - side effect of certain drugs - certain food stuffs changing intestine flora - others. In our clinic, I recommend to undertake a stool microscopy along with colonoscopy examination for the final work up and management guidelines. Hope this information will help you. Thanks.