Why Won't My Anal Fissure Heal?

Introduction

A new anal fissure — one that's been around for less than 6–8 weeks — heals on its own in about half of cases with stool softening alone. But a chronic fissure (one that's been there longer, or one that has a white, fibrous base with raised edges and a small skin tag at the lower end) is a different beast. It can hang around for months or years, causing the same agonising pain with every bowel motion, and stubbornly refuses to heal no matter how careful you are.

There is a clear biological reason why this happens — and it can be treated directly. This article explains the cycle that keeps your fissure open, why simple self-care often isn't enough on its own, and what the path to healing actually looks like.

What is a chronic anal fissure?

A chronic anal fissure is a small tear in the lining of the back passage that has been there long enough to stop looking like a fresh wound. Almost always, it's in the midline at the back (the 6 o'clock position). What distinguishes it from a new fissure is its appearance: the base becomes pale and fibrous (you may be able to see the white fibres of the sphincter muscle); the edges look raised and thickened; and there's often a small skin tag at the lower end (called a sentinel pile) and a swollen tissue fold at the upper end.

These changes aren't just cosmetic — they reflect a wound that has been repeatedly injured, tried to heal, and failed, leaving behind scar-like tissue that actively gets in the way of healing properly.

Why fissures become chronic — the spasm-ischaemia cycle

The reason your fissure won't heal comes down to the internal anal sphincter — the smooth muscle ring just beneath the lining of the back passage that stays contracted to keep the anus closed. When a fissure forms, this muscle goes into spasm as a protective reflex. The spasm then does two things that keep the fissure from ever closing:

First, the increased muscle tension keeps the wound edges pulled apart every time you have a bowel motion, so they can't come together and close. Second, the back part of the anal canal (where fissures almost always form) already has a relatively limited blood supply, and the spasm squeezes even that. Without good blood flow, tissue simply cannot heal — in any part of the body.

The result is a wound that is physically prevented from healing by the very muscle that's supposed to protect it. Every treatment for a chronic fissure ultimately targets this cycle — reducing the spasm to lower the internal pressure and restore blood flow to the area.

Symptoms of a non-healing fissure

• Severe pain with every bowel motion — typically a sharp tearing sensation, followed by a burning or throbbing ache lasting 30 minutes to several hours — with no real improvement over weeks
• A frustrating pattern of slight improvement followed by re-injury (often when a stool is slightly firmer than usual)
• A small lump you can feel near the anus — the sentinel skin tag at the lower end of the fissure
• Putting off going to the toilet more and more, which leads to harder stools and makes everything worse
• Dreading every toilet visit — the anxiety about the next bowel motion is real and significant, and it takes a genuine toll on everyday life

Causes — why it persisted

Beyond the sphincter-spasm cycle, several specific things can prevent a fissure from healing:

Inconsistent or too-short a course of treatment

This is the most common reason. Topical creams that relax the internal sphincter — such as diltiazem — need to be applied twice daily, consistently, for 8–12 weeks. Many people apply it irregularly, or stop when they start to feel a little better (which is not the same as healed). Even a few days of inconsistency can allow the sphincter spasm to reset and restart the cycle.

Ongoing stool trauma

A wound can't heal if it's being re-injured every day. If your stool isn't soft enough, every bowel motion re-tears the fissure before it has any chance to close. Softening your stool typically requires both a high-fibre diet and a stool softener (such as lactulose or macrogol) — neither alone is usually enough for a chronic fissure.

High resting sphincter tone

Some people naturally have higher muscle tension in their internal sphincter than average. This makes them more prone to fissures in the first place, and also means the elevated pressure is harder to normalise with cream alone. If this is the case for you, Botox injection is often the key — it reliably lowers sphincter pressure in a way that cream sometimes can't achieve.

Crohn's disease

If your fissure is in an unusual position (not the back midline), if you have more than one fissure, or if they're unusually deep or complex, Crohn's disease is worth considering. Fissures caused by Crohn's behave differently — they need the underlying inflammatory condition to be treated, and standard fissure treatments on their own often don't work.

Previous treatment with steroid cream

Steroid-containing creams (often prescribed for what looked like haemorrhoids) can actually impair wound healing and make a chronic fissure worse. If you've been using haemorrhoid cream with steroids on what turns out to be a fissure, this may be part of the reason it hasn't healed.

When to worry

• No improvement after 8 weeks of consistent topical treatment — it's time for a specialist review
• Pain that's getting worse rather than staying the same — this may indicate a secondary infection or abscess forming
• Fever, swelling around the anus, or a smelly discharge — see a doctor urgently as this may be a perianal abscess or fistula
• Fissure that's not in the back midline — worth being assessed for Crohn's disease
• Change in your usual bowel habit, or blood mixed through the stool (not just on the paper) — needs assessment to make sure nothing else is going on

Treatment options for chronic fissures

Stool optimisation — the foundation of everything

This step is non-negotiable, regardless of which other treatment you're having. A daily stool softener (lactulose 10–20ml, or macrogol 1–2 sachets), increased dietary fibre (aim for 25–35g per day), and drinking enough water (1.5–2 litres per day) ensure each bowel motion is soft and as low-trauma as possible. Without this in place, even the most effective sphincter treatment will be limited by the fissure being re-torn every day.

Topical diltiazem 2% — the standard first-line treatment in Australia

Applied inside and around the back passage twice daily for 8–12 weeks. Diltiazem is a type of muscle relaxant (a calcium channel blocker) that works specifically on smooth muscle — including the internal sphincter. With consistent use, 65–80% of chronic fissures heal. One important thing to know: if the cream stings, or you don't feel like it's "working" after 2–3 weeks, that doesn't mean it has failed. It typically takes 6–10 weeks of application for the effect on healing to show up. Headaches are an uncommon side effect (unlike GTN cream, which causes headaches in up to half of people who use it).

Botulinum toxin (Botox) injection

When cream hasn't healed the fissure after a full 10–12 week course, the next step is a Botox injection into the internal sphincter. A small dose is injected under brief anaesthesia — it's a short procedure, not a major operation. The Botox temporarily relaxes the sphincter for 3–4 months, which is usually long enough for the fissure to fully heal. About 75–80% of fissures heal with Botox. Around 10% of people notice some temporary minor leakage of liquid stool or wind while the Botox is active — this resolves as it wears off.

Lateral internal sphincterotomy (LIS)

If cream and Botox haven't been enough, lateral internal sphincterotomy (LIS) is the surgical solution. A small portion of the internal sphincter is carefully divided under general anaesthetic — it's a day procedure, meaning you go home the same day. Over 90% of fissures heal after LIS, and the pain relief is often dramatic within just a few days of the operation. The main consideration is a small but permanent reduction in sphincter strength; for most people this is not noticeable, but around 5% experience some minor difficulty controlling wind or liquid stool — this should be discussed with your surgeon beforehand, especially if you have any existing concerns about continence.

When surgery is needed

LIS is recommended when a fissure hasn't healed after proper courses of both topical diltiazem and Botox. If your quality of life is severely affected — you're dreading every toilet trip, avoiding going to dangerous extremes, or the post-defecation pain is consuming hours of every day — the threshold for moving to surgery sooner may be lower. LIS provides rapid, reliable, lasting relief that genuinely is hard to match with non-surgical options for fissures that simply won't respond.

Frequently asked questions