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Beverly Hills · 435 N. Bedford Dr., Suite 308Mon–Fri 9:00 am – 5:00 pmMost PPO insurance accepted
Allen KamravaMD · MBA · FACS · FASCRS

Procedure

In office

Chemical Sphincterotomy (Botulinum Toxin)

A quick office injection that relaxes the tight sphincter muscle for a few months — long enough for the fissure to heal — without cutting any muscle.

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Setting
In office
Anesthesia
Usually none needed — it's a brief injection; a topical numbing agent can be used
Back to work
Most patients return to work and normal activity the same day
Pain relief
Little to none afterward — over-the-counter relievers if needed
Success rate
60-80%
Recurrence
Up to 40%

What it is

What is a Chemical Sphincterotomy?

A chemical sphincterotomy is a non-surgical procedure used to treat chronic anal fissures. It involves the injection of Botulinum Toxin A (Botox) directly into the internal anal sphincter muscle. The toxin works by temporarily blocking the release of acetylcholine, a neurotransmitter that causes muscle contraction. This results in a temporary and reversible paralysis (chemodenervation) of the sphincter muscle. The relaxation of the hypertonic sphincter reduces pain, improves blood flow to the fissure, and allows the fissure to heal without the need for a surgical incision.

Am I a candidate?

Who is a Good Candidate for This Procedure?

This procedure is an ideal option for patients with chronic anal fissures who have failed to heal after at least 6-8 weeks of conservative medical management, such as topical nitrates or calcium channel blockers. It is a particularly good alternative for patients who wish to avoid the small but permanent risk of incontinence associated with a surgical lateral internal sphincterotomy. It may also be considered in patients with a higher baseline risk for incontinence, such as multiparous women or those with pre-existing sphincter weakness.

How it's done

  1. 1A brief exam first — the whole visit takes only minutes.
  2. 2A small dose of botulinum toxin is injected directly into the internal sphincter muscle, usually on both sides.
  3. 3There is no incision and nothing to heal from the procedure itself — the medicine simply relaxes the muscle over the following days.
  4. 4Most patients go straight back to their day.

What to expect

  1. Same day

    Back to work and normal activity for most patients.

  2. First week

    The muscle gradually relaxes; fissure pain typically eases over several days as the pressure comes down.

  3. Following weeks

    With the pressure lowered, the fissure has its best chance to heal — and many do. Fiber, fluids, and soft stools protect it while it heals.

  4. A few months

    The effect wears off gradually and the muscle's full strength returns — by then the fissure has often healed. If it hasn't, that isn't a failure on your part — a small operation is the reliable next step. A follow-up visit checks on it.

Risks & considerations

What are the Risks?

Chemical sphincterotomy is a very safe procedure with a low risk of side effects, which are almost always temporary and mild. Potential risks include:

  • Temporary Incontinence: A small number of patients (up to 18%) may experience temporary, minor incontinence to flatus or seepage. This is the most common side effect and typically resolves within a few weeks to months as the effect of the toxin wears off.
  • Pain or Bruising: Mild discomfort or bruising at the injection site can occur but is usually minimal and short-lived.
  • Urinary Hesitancy: Very rarely, the toxin can affect the muscles involved in urination, leading to temporary difficulty.
  • Fissure Recurrence: While often effective, the fissure may fail to heal or may recur after the effects of the botulinum toxin wear off. This occurs in up to 40% of patients.
  • Allergic Reaction: Allergic reactions to Botulinum Toxin are extremely rare.

Sources

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