What is an anal fissure? 

An anal fissure is a tear in the lining of the lower rectum (anus) that causes pain during bowel movements. It is a common condition. Anal fissures do not lead to more serious conditions such as colon cancer.

Most anal fissures heal with home treatment after a few days or weeks (acute anal fissures). Occasionally a fissure takes more than 6 weeks to heal (chronic anal fissure), in which case it usually requires medication to heal. Surgery may be necessary for fissures that do not heal with medication.

Anal fissures affect people of all ages, particularly young and otherwise healthy people. They are equally common in men and women.

Sometimes an anal fissure and a hemorrhoid develop at the same time.

What causes an anal fissure?

Anal fissures are caused by vigorous stretching of the anal canal. A fissure may develop if you are constipated and try to pass a large, hard stool; if you don't relax your anal muscles (sphincter muscles) during a bowel movement; or sometimes after repeated diarrhea.

Many experts believe the most common cause is excessive tension in the two muscular rings (sphincters) controlling the anus. The external anal sphincter is under your conscious control. However, the internal anal sphincter is not under your control. This muscle remains under pressure, or tension, all of the time. A fissure may develop if the internal sphincter's resting pressure becomes too high, causing spasm and reducing blood flow to the anus.

Trauma also can cause fissures. During childbirth, 11% of women develop anal fissures.1 Fissures can also be caused by digital insertion (as during an examination), foreign body insertion, or anal intercourse.

In some cases, an anal fissure may be caused by Crohn's disease, an inflammatory bowel disease (IBD) that causes bloody diarrhea, abdominal pain, fever, weight loss, and fissures or fistulas near the anus.

A low-fiber diet may play a role in the development of fissures.

What are the symptoms?

An anal fissure causes a sharp, stinging, or burning pain during a bowel movement. The pain, which can be severe, may last for a few hours.

Fissures may itch. They often bleed lightly or cause a yellowish discharge. You may see a small spot of bright red blood on toilet tissue or a few drops in the toilet bowl. The blood is separate from the stool. Blood mixed with stool indicates some other condition, possibly inflammatory bowel disease (IBD) or colon cancer. You should contact a health professional if you have bleeding with bowel movements or dark, bloody stools.

Occasionally an anal fissure may be a painless wound that won't heal and that bleeds intermittently but causes no other symptoms.

How is an anal fissure diagnosed?

Our doctors can diagnose an anal fissure from symptoms and by looking at the anus. Usually, the health professional can see the fissure by gently separating the buttocks.

A health professional may use a gloved finger (digital rectal examination) or a lighted instrument (anoscope) to examine the fissure. However, if the fissure is extremely painful, the health professional will usually wait until it has begun to heal before performing a rectal exam or using an anoscope (anoscopy) to rule out other problems. A topical anesthetic may be used if an immediate examination is necessary.

During an exam, a health professional can also determine whether another condition may be causing the fissure. If you have several fissures or have one or more in an area of the anus where fissures usually do not occur, you may have another condition such as IBD, syphilis, a suppressed immune system, tuberculosis, HIV infection, or anal cancer. Most fissures occur along the midline-the top or bottom-of the anus.

How is it treated?

Most acute fissures need some home treatment, including soaking in a shallow tub of warm water (sitz bath) several times a day, increasing fiber in the diet, and taking stool softeners or laxatives. Some people find relief within a day or two of home treatment. Although your pain may go away, it may take several weeks for the fissure to heal completely. Occasionally fissures heal without treatment.

Try to prevent constipation, which can keep a fissure from healing. The pain of a fissure may make you anxious about having bowel movements. However, trying not to have bowel movements will only increase constipation and create a cycle that keeps the fissure open and painful.

Drinking lots of water or other fluids also will make stools soft and easy to pass.

You may want to use a nonprescription ointment such as zinc oxide, Preparation H, Anusol, or 1% hydrocortisone to soothe anal tissues. However, some evidence suggests that anesthetic preparations such as Anusol may delay healing.

If a fissure lasts a long time (chronic), you probably will need a prescription medication such as nitroglycerin ointment or the high blood pressure medications nifedipine and diltiazem, which are taken as pills. Nifedipine is also available as an ointment, but diltiazem is not yet available as an ointment in the United States. These medications may decrease the resting pressure of the internal anal sphincter, which can allow the edges of the fissure to come together and heal.

Botulinum toxin (Botox) is gaining wider use as a treatment for chronic anal fissures. An injection of Botox temporarily paralyzes the internal anal sphincter, reducing resting pressure and allowing the fissure to heal.2

You may need to consider surgery if medications do not stop your symptoms. The most commonly used surgery is lateral internal sphincterotomy. In this procedure, a health professional cuts into part of the internal sphincter to relax the spasm that is causing the fissure.