Botox For Anal Fissure Explained



Chronic anal fissure is a painful condition that may prove difficult to treat for some patients.

Doctor Medica team

Chronic anal fissure is a painful condition that may prove difficult to treat for some patients. Interestingly, Botox, a popular cosmetic treatment, may be the treatment patients turn to help manage their pain and resolve the disorder. In this article, various aspects pertaining to the use of Botox to treat chronic anal fissure will be discussed, including how it treats the condition, who are good candidates for treatment, as well as its role in the management of this chronic disorder.

How do anal fissures develop?

Anal fissures are ulcers or tears in the distal anal canal that extends below the dentate line to the anal verge. Patients with anal fissure commonly have pain and bleed upon defecation. The pathogenesis and etiology of anal fissures are unclear, but they usually begin with some sort of trauma to the lining of the anus; for instance, the defecation of hard, dry stool can be such a trauma. The initial trauma causes an anal sphincter spasm and a rise in sphincter muscle pressure, the latter of which also leads to a decrease in blood flow to the affected site, thereby further exacerbating the condition and preventing proper healing of the wound. Subsequent bowel movements further perpetuate this cycle.

The majority of anal fissures will resolve without the need for medical intervention. Non-operative measures can help to offset the symptoms of pain and bleeding and allow acute fissures to resolve on their own.  For the most part, the healing of acute anal fissures can be assisted by certain dietary measures, such as the adoption of a high-fiber diet, and stool softeners. Pain can be alleviated with topical anesthetics and lidocaine, and sitz baths can help relax the anal muscles to help further promote healing.

How does Botox work to treat chronic anal fissure?

An anal fissure can be chronic, with the condition lasting 8–12 weeks. Chronic anal fissures can differ from acute cases of chronic fissure on the basis of excess swelling and the presence of scar tissue. Chronic anal fissure occurs due to the perpetuation of inflammation caused by a vicious cycle of pain, spasm, and tissue ischemia, making chronic fissures difficult to treat. As such, chronic anal fissures are associated with the persistent spasm of the internal anal sphincter, which is reflected in elevated resting anal pressures.

Current approaches to treatment are focused on the relief of muscle spasm in order to allow the fissure to heal. Surgical approaches such as sphincterotomy involve the cutting of the internal sphincter to relax the muscle, thereby stopping the spasm. Such surgical approaches are usually successful in treating chronic anal fissure, but they are associated with permanent complications, such as fecal incontinence, that can be severe. A study determined that the rates of incontinence were as high as 66% among cases of surgical sphincterotomy. Due to these high rates of adverse events, chemical means of stopping muscle spasms have been pursued as an alternative to surgery. From there, two viable methods of therapy have emerged: topical nitroglycerin ointments, and botulinum toxin injections into the anal sphincter.

Botulinum toxin works on the muscle(s) it is injected into by chemically denervating them, thereby preventing the affected muscle(s) from contracting. In this manner, Botox doesn’t just provide symptomatic relief; it also helps to resolve the condition by allowing the fissure to heal. Compared with nitroglycerin application, Botox produces fewer side effects and results in a lower rate of recurrence.

What is the treatment procedure like?

The toxin is administered via injection into the muscles involved in producing the spasm that prolongs the duration of the fissure. The procedure can be conducted as an outpatient procedure or an in-office, same-day treatment, with no associated downtime required after the procedure.

When using Botox to treat chronic anal fissure, between 20–25 units of Botox is injected into the internal sphincter, with the injection guided by eye and digital examination. The total dose comprises of eight Units into either side of the sphincter and nine Units into the anterior verge. If the practitioner is not familiar with puncturing the sphincter, injection can be conducted under electromyographic guidance or with anal endosonography. It is important that the injections not be too deep, as that may cause the toxin to diffuse into the puborectalis muscle, which may lead to incontinence.

The effect(s) of Botox treatment will usually be apparent after a few days in the form of pain reduction. These benefits typically last a few months, but this length is dependent on multiple factors, especially the dose injected. In the event that recurrence of the anal fissure occurs, repeat treatments may be performed.

Who are ideal candidates to receive Botox treatment for their chronic anal fissure?

Botox is often recommended to patients who failed to respond to the conventional topical measures of managing this condition, which include the use of nitroglycerin ointment and calcium channel blockers. Botox is suitable as a second-line therapy and should be carried out before any surgical procedure.

Some patients are not ideal candidates for Botox treatment. This includes patients with bleeding disorders or ones who are taking anticoagulants. Likewise, patients with abscesses at the proposed site of treatment should not receive therapy due to the risk of infection.


Chronic anal fissure is a difficult condition to treat due to its self-perpetuating nature that is mainly facilitated by the constant contractions of the anal sphincter. Botulinum toxin injections are a non-surgical, effective, and relatively long-term treatment that patients with this painful condition should consider.

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