An anal fissure is a small tear in the thin, moist tissue (mucosa) that lines the anus. An anal fissure may occur when you pass hard or large stools during a bowel movement. Anal fissures typically cause pain and bleeding with bowel movements. You also may experience spasms in the ring of muscle at the end of your anus (anal sphincter).
Anal fissures are very common in young infants but can affect people of any age. Most anal fissures get better with simple treatments, such as increased fibre intake or sitz baths.
Common causes of anal fissure include:
Passing large or hard stools
Constipation and straining during bowel movements
Inflammation of the anorectic area, caused by Crohn's disease or another inflammatory bowel disease
Signs and symptoms of an anal fissure include:
Pain, sometimes severe, during bowel movements.
Pain after bowel movements that can last up to several hours.
Bright red blood on the stool or toilet paper after a bowel movement.
Itching or irritation around the anus.
A visible crack in the skin around the anus.
A small lump or skin tag on the skin near the anal fissure.