Definition

An anal fissure is a small split or tear in the thin moist tissue (mucosa) lining the lower rectum (anus).

Alternative Names

Fissure in ano; Anorectal fissure; Anal ulcer

Causes

Anal fissures are very common in infants, but they may occur at any age.

In adults, fissures may be caused by passing large, hard stools, or having diarrhea for a long time. Other factors may include:

• Decreased blood flow to the area
• Too much tension in the sphincter muscles that control the anus

The condition affects males and females equally. Anal fissures are also common in women after childbirth and in people with Crohn disease.

Symptoms

An anal fissure can be seen as a crack in the anal skin when the area is stretched slightly. The fissure is almost always in the middle. Anal fissures may cause painful bowel movements and bleeding. There may be blood on the outside of the stool or on the toilet paper (or baby wipes) after a bowel movement.

Symptoms may begin suddenly or develop slowly over time.

Exams and Tests

Your health care provider will perform a rectal exam and look at the anal tissue. Other medical tests that may be done include:

• Anoscopy -- examination of the anus, anal canal, and lower rectum
• Sigmoidoscopy -- examination of the lower part of large intestine
• Biopsy -- removal of rectal tissue for examination
• Colonoscopy -- examination of the colon

Treatment

Most fissures heal on their own and do not need treatment.

To prevent or treat anal fissures in infants, be sure to change diapers often and clean the area gently.

CHILDREN AND ADULTS

Worrying about pain during a bowel movement may cause a person to avoid them. But not having bowel movements will only cause the stools to become even harder, which can make the anal fissure worse.

Prevent hard stools and constipation by:

• Making dietary changes -- eating more fiber or bulk, such as fruits, vegetables, and grains
• Drinking more fluids
• Using stool softeners

Ask your provider about the following ointments or creams to help soothe the affected skin:

• Numbing cream, if pain interferes with normal bowel movements
• Petroleum jelly
• Zinc oxide, 1% hydrocortisone cream, Preparation H, and other products

A sitz bath is a warm water bath used for healing or cleansing. Sit in the bath 2 to 3 times a day for 10 to 15 minutes each time. The water should cover only the hips and buttocks.

If the anal fissures do not go away with home care methods, treatment may involve:

• Botulinum toxin injections into the muscle in the anus (anal sphincter)
• Minor surgery to relax the anal muscle
• Prescription creams, such as nitrates or calcium channel blockers, applied over the fissure to help relax the muscles

Outlook (Prognosis)

Anal fissures often heal quickly without any more problems.

People who develop fissures once are more likely to have them in the future.

References

Downs JM, Kulow B. Anal diseases. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 129.

Hyman N, Umanskiy K. Anus. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 21st ed. St Louis, MO: Elsevier; 2022:chap 53.

Kliegman RM, St. Geme JW, Blum NJ, et al. Surgical conditions of the anus and rectum. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 392.