Why is my poo black?

Not sure?: Are you taking iron, peptobismal or other meds that can turn stool black? If the stool has a foul smell, is black and sticky - that could be a sign of gastrointestinal bleeding & would merit prompt medical evaluation. Take care.

Black stool.: Black stool could suggest bleeding from the upper digestive tract, such as from an ulcer. You need an evaluation by a Gastroenterologist - perhaps an EGD. Do you take aspirin, as medications like aspirin can cause ulcers.