Melanosis coli is a condition in which islands of black pigmentation accumulate in the interior lining of the large bowel. They are easy to see when viewed through a colonoscope.

The pigment is a substance known as lipofucsin. Produced by dying cells, this substance is gobbled up by macrophages. These cells are the "carpet sweepers" in our tissues. Macrophages filled with black pigment tend to cluster into islands. This is what the doctor sees during the colonoscopy.

Melanosis coli is almost always caused by frequent use of laxatives or herbal products that contain anthraquinones as their active ingredient.

Melanosis coli is not a sign of cancer. And it does not cause bowel inflammation. Mainly, it shows that the person is using, and possibly abusing, laxatives or other products.

Any treatment for constipation should be aimed at improving bowel habits without the use laxatives or other products.