Whats wrong if my poop is black?

Danger: Black bm's should be considered digested blood until proven other wise. Sudden death from bleeding ulcers, slow death from cancer...Ect, get to your doc. They can diagnose this in a timely bases. There are benign causes, like excessive pepto-bismol intake.

See md: Could be blood in the stools which could mean some serious illness. Also taking iron tabs can make stool black.

Depends: Dark stools may be caused by digested blood from a stomach bleed. A test for fecal occult blood should answer this. Some foods like blueberries or meds like pepto-bismol can also darken stools. See your doc and share any symptoms you have so you can get a good workup.