Medically reviewed by Kumkum S. Patel, MD Noticing black stool can be alarming, but the cause isn’t always serious. Sometimes, black stool can stem from harmless factors like diet or medication.

Discover the top causes of black poop like diet, supplements, and gut health conditions, plus the best treatment options ...

Or you may easily see it as red blood, or black tar-like bowel movements ... Other tests require you to collect stool samples on more than one day. You then send the samples, in a special ...