Anal fissures are tears in the skin overlying the anal sphincter, usually due to increased tone of the anal sphincter muscles, and a failure of these muscle to relax. Anal fissures cause pain during defecation and bleeding from the anus.
Review Date 5/6/2022
Updated by: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.