Melanosis Coli: Symptoms & Signs

Medically Reviewed on 8/6/2021

Melanosis coli is a condition in which dark pigment is deposited in one of the lining layers of the large intestine (bowel). This results in a characteristic dark brown to black discoloration of the lining of the large intestine. This condition is sometimes called pseudomelanosis coli because the pigment deposits consist of a pigment known as lipofuscin and do not actually contain the skin pigment melanin as implied by the term "melanosis." The condition may be reversed upon discontinuation of laxative use.

Melanosis coli does not cause symptoms or signs. It is discovered upon colonoscopy or other examination of the tissues of the large intestine. The dark color of the intestinal lining may be uniform or patterned and can vary in intensity. The intensity and pattern of the pigment deposits may even vary among different sites in the colon of a single person.

Cause of melanosis coli

Melanosis coli is caused by chronic use of laxatives of the anthranoid group, such as senna (sennosides: Senokot, Senokot Extra Strength, and others) and rhubarb derivatives.

Other melanosis coli symptoms and signs

  • Melanosis Coli Does Not Cause Signs or Symptoms


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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.