Dark Stool Causes: Understanding Color Changes This is melanosis colia result of long term stimulant laxative use (like Senekot). Have you ever heard of melanosis coli? It's not just staining. It's your colon screaming for help. Senekot (a Poop Patrol: Spotting Changes that Need Attention Melanosis coli and colorectal cancer: Coincidence or correlated? ScienceDirect MELANOSIS COLI** Melanosis coli is a disorder of pigmentation of the bowel wall. Histology demonstrates pigment laden macrophages It is associated with laxative abuse, especially **anthraquinone compounds such as senna**