Overview

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 fiber intake or sitz baths. Some people with anal fissures may need medication or, occasionally, surgery.

Anal fissure care at Mayo Clinic

Symptoms

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

When to see a doctor

See your doctor if you have pain during bowel movements or notice blood on stools or toilet paper after a bowel movement.

Causes

Common causes of anal fissure include:

  • Passing large or hard stools
  • Constipation and straining during bowel movements
  • Chronic diarrhea
  • Inflammation of the anorectal area, caused by Crohn's disease or another inflammatory bowel disease
  • Childbirth

Less common causes of anal fissures include:

  • Anal cancer
  • HIV
  • Tuberculosis
  • Syphilis
  • Herpes

Risk factors

Factors that may increase your risk of developing an anal fissure include:

  • Infancy. Many infants experience an anal fissure during their first year of life; experts aren't sure why.
  • Aging. Older adults may develop an anal fissure partly due to slowed circulation, resulting in decreased blood flow to the rectal area.
  • Constipation. Straining during bowel movements and passing hard stools increase the risk of tearing.
  • Childbirth. Anal fissures are more common in women after they give birth.
  • Crohn's disease. This inflammatory bowel disease causes chronic inflammation of the intestinal tract, which may make the lining of the anal canal more vulnerable to tearing.
  • Anal intercourse.

Complications

Complications of anal fissure can include:

  • Failure to heal. An anal fissure that fails to heal within six weeks is considered chronic and may need further treatment.
  • Recurrence. Once you've experienced an anal fissure, you are prone to having another one.
  • A tear that extends to surrounding muscles. An anal fissure may extend into the ring of muscle that holds your anus closed (internal anal sphincter), making it more difficult for your anal fissure to heal. An unhealed fissure can trigger a cycle of discomfort that may require medications or surgery to reduce the pain and to repair or remove the fissure.

Prevention

You may be able to prevent an anal fissure by taking measures to prevent constipation. Eat high-fiber foods, drink fluids and exercise regularly to keep from having to strain during bowel movements.