Injections of botulinum toxin (Botox) may help heal a tear (fissure) in the anus.
The internal anal sphincter, one of two muscles that control the anus, is always under tension. If this tension (also called resting pressure) is too high, spasms and reduced blood flow can cause an anal fissure or prevent an existing one from healing. Botulinum toxin, the poison that causes botulism, temporarily paralyzes the internal anal sphincter. This reduces the spasm and allows the fissure to heal.
Botulinum injections may be more helpful than nitroglycerin ointment, but the studies do not all agree.1 One study found that two botulinum injections worked better than nitroglycerin ointment to heal long-term (chronic) fissures.2 However, fissures may return after treatment with Botox is discontinued.
The people in this study had no side effects, such as inability to control gas or stool. However, other studies have reported that some people have temporary inability to control gas or (rarely) stool. Pain from the injections may occur. Infection or hematoma (a pooling of blood in body tissue) at the injection site is a slight risk.
Citations
Nelson R (2005). Non-surgical therapy for anal fissure. Cochrane Database of Systematic Reviews (2). Oxford: Update Software.
Brisinda G, et al. (1999). A comparison of injections of botulinum toxin and topical nitroglycerin ointment for the treatment of chronic anal fissure. New England Journal of Medicine, 341(2): 65–69.
| Author | Ralph Poore |
| Editor | Kathleen M. Ariss, MS |
| Associate Editor | Pat Truman |
| Primary Medical Reviewer | Kathleen Romito, MD - Family Medicine |
| Specialist Medical Reviewer | C. Dale Mercer, MD, FRCSC, FACS - General Surgery |
| Last Updated | June 16, 2006 |