Which has a higher success rate — botox or LIS?

LIS has a higher success rate for chronic fissure healing, generally reported in the range of 90 to 95 percent. Botox success rates are lower, typically 50 to 80 percent depending on the study and the definition of success. However, botox is reversible and carries less risk, which is why it is often tried first.

Is botox always tried before LIS?

Not always, but it is a common pathway. Many clinicians recommend trying botox first because it is less invasive and reversible. If botox does not work or the fissure recurs, LIS is then considered. Some clinicians may recommend going directly to LIS for certain patients, particularly those with severe, longstanding fissures.

What is the continence risk with each?

Both procedures carry some risk of temporary changes to gas control. For botox, this is temporary by nature — the botox wears off. For LIS, any continence change is potentially permanent because the sphincter is physically divided. The risk with LIS is generally low and relates mainly to minor gas incontinence, but it is not zero.

Can I have botox more than once?

Yes. Some people have a second botox injection if the first was partially effective or if the fissure recurs after initial healing. There is no strict limit, though the decision to repeat versus move to surgery is made on a case-by-case basis.

How long does botox last?

The muscle-relaxing effect of botox typically lasts two to four months. During this window, the fissure has the opportunity to heal. Once the botox wears off, the sphincter returns to its normal tone. If the fissure has healed during that window, the benefit is permanent.

Botox vs LIS surgery for fissure

At a glance

For people with a chronic anal fissure that has not responded to conservative treatment, the two main procedural options are botox injection and lateral internal sphincterotomy (LIS). Both aim to relax the internal sphincter muscle to break the fissure-spasm cycle and allow healing.

They differ significantly in approach, success rate, risk profile, and reversibility. This guide compares them clearly to help you understand the trade-offs before discussing with your surgeon.

How each procedure works

Botox

Botulinum toxin is injected into the internal sphincter muscle, temporarily paralysing it. This relaxes the spasm, increases blood flow to the fissure, and creates a window for healing. The effect lasts two to four months, after which the muscle returns to normal function.

LIS (lateral internal sphincterotomy)

A small portion of the internal sphincter muscle is surgically divided (cut). This permanently reduces the resting pressure of the sphincter, breaking the spasm cycle and allowing the fissure to heal. The effect is permanent.

The comparison

Success rate

LIS: approximately 90 to 95 percent for chronic fissure healing. It is the most effective surgical treatment available.

Botox: approximately 50 to 80 percent, depending on the study and definition of success. Some people heal completely. Others experience partial improvement. Some do not respond.

Reversibility

LIS: permanent. The muscle that is divided does not regrow. This is a one-way decision.

Botox: temporary. The effect wears off in two to four months. If there are unwanted effects, they resolve on their own.

Continence risk

LIS: there is a small but real risk of minor continence changes — most commonly difficulty controlling gas. The risk of significant faecal incontinence is very low but not zero. This risk is permanent.

Botox: temporary continence changes are possible while the botox is active but resolve as the effect wears off. This temporary nature makes botox lower-risk from a continence perspective.

Recovery

LIS: a surgical procedure requiring anaesthesia, typically as a day case. Recovery takes two to four weeks for most people, with pain during the first week.

Botox: a brief injection, sometimes done under sedation, sometimes in clinic. Recovery is minimal — most people return to normal activities within a day or two.

Pain

LIS: post-operative pain for several days to a week, though many people describe it as less severe than the chronic fissure pain they were living with.

Botox: the injection itself causes minimal pain. Post-procedure discomfort is typically slight.

Recurrence

LIS: recurrence rates are low — the permanent sphincter modification makes re-tearing less likely.

Botox: recurrence is more common, as the sphincter returns to its normal pressure once the botox wears off. Some people need a second injection or proceed to LIS.

How people typically decide

The decision between botox and LIS often follows a pattern:

Try botox first

Many clinicians recommend botox as a first step because:

It is less invasive
It is reversible
If it works, the fissure heals without permanent sphincter modification
If it does not work, LIS remains available

Go directly to LIS

Some clinicians recommend LIS directly when:

The fissure is severe and longstanding
Conservative treatment and topical therapies have already failed
The patient prefers a single, definitive procedure
The anatomy and sphincter assessment suggest low continence risk

Factors that influence the choice

How long the fissure has been chronic — longer-standing fissures may be less likely to respond to botox alone
Sphincter pressure — very high resting pressure may respond better to LIS
Continence concerns — people with any existing continence issues may prefer the reversible option
Personal preference — some people want to try the least invasive option first; others want the highest chance of resolution

The honest picture

Neither option is perfect.

Botox offers safety and reversibility at the cost of a lower success rate and the possibility of needing further treatment.

LIS offers the highest success rate at the cost of a permanent change to the sphincter and a small but non-zero risk of continence change.

Most people who go through this decision describe it as genuinely difficult. There is no obviously right answer — it depends on your specific situation, your risk tolerance, and your priorities. This is a conversation to have thoroughly with your surgeon, who can assess your fissure, your sphincter, and your individual risk profile.