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Health condition · Clinically reviewed

Anal fissure, from a tearing pain to a healed anal canal.

Most fissures heal within weeks with soft stools and simple topical care. A clear ladder exists for the ones that do not, and it works.

Jump to treatment
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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE CKS, ACPGBI and peer-reviewed colorectal sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including topical GTN, diltiazem, botulinum toxin and sphincter-preserving surgery.

Key facts

Anal fissure at a glance.

The essentials in plain English: what it is, acute versus chronic, and how it is treated in UK colorectal care today.

  • What it is

    A linear tear in the anoderm of the anal canal, distal to the dentate line, most often posterior midline in around 90% of cases.

  • Acute vs chronic

    Acute fissures heal within six to eight weeks. Chronic fissures persist beyond that and show a sentinel skin tag, hypertrophied anal papilla and fibrotic edges.

  • Classic symptoms

    A searing, tearing pain during defecation with bright red blood on the paper, often followed by hours of spasm and a fear of the next bowel motion.

  • Atypical fissure

    A lateral fissure, or multiple fissures, should prompt review for Crohn's disease, HIV, tuberculosis, syphilis and anal malignancy.

  • First-line care

    Stool softeners, dietary fibre, hydration, warm sitz baths and topical local anaesthetic settle most acute fissures within weeks.

  • Escalation

    Topical GTN or diltiazem, then botulinum toxin, then lateral internal sphincterotomy or an advancement flap for refractory chronic disease.

Why this guide matters

A stepped ladder, not a lifetime of pain.

Anal fissures are common, treatable and often cured at the first rung of the ladder. The three points below shape everything else on this page.

  • Soft stools break the cycle

    A hard stool tears the anoderm; the spasm that follows prevents healing. Softening the stool is the single most useful intervention.

  • Topicals heal most chronic fissures

    GTN and diltiazem relax the internal sphincter enough to restore blood flow. Given six to eight weeks they close most chronic fissures.

  • Surgery is safe when it's needed

    Botulinum toxin and lateral internal sphincterotomy have transformed outcomes for refractory fissures. Modern colorectal care is very good at this.

How the diagnosis is made

From first tear to a clear plan.

The steps a UK GP or colorectal surgeon will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    Careful clinical history

    Character and timing of the pain, colour and volume of bleeding, bowel habit, obstetric history and any red flags for inflammatory or malignant disease.

  2. 02

    Assessing

    Gentle external inspection

    Simple parting of the buttocks often reveals a posterior midline tear and a sentinel tag without any need to touch the fissure itself.

  3. 03

    Assessing

    Deferred digital rectal exam

    A digital rectal examination is often deferred if the anal canal is too painful. Forcing it adds nothing and erodes trust.

  4. 04

    Confirming

    Examination under anaesthesia

    If the diagnosis is uncertain, an EUA with proctoscopy allows a full look at the anal canal without causing distress.

  5. 05

    Confirming

    Hold off routine investigations

    A typical posterior fissure needs no imaging or endoscopy. Atypical or lateral fissures warrant biopsy and targeted tests.

  6. 06

    Planning

    Colonoscopy for red flags

    Change in bowel habit, weight loss, iron-deficiency anaemia or a family history of bowel cancer point to colonoscopy, not fissure care alone.

  7. 07

    Planning

    Shared plan for the ladder

    Once the diagnosis is settled, you and your clinician agree how far up the treatment ladder to go and when to review.

Typical timeline: a first visit to a settled plan in a single appointment, with escalation reviewed at eight weeks.

Symptoms

What an anal fissure actually feels like.

The classic mix of tearing pain, bright red bleeding and reflex spasm, and the features that mark a fissure as truly chronic.

  • Searing pain on defecation

    A tearing, glass-like pain at the moment of passing stool that can outlast the bowel motion by hours.

  • Bright red blood on paper

    Fresh red blood on the paper or a streak on the stool, rarely enough to drip into the pan.

  • Anal spasm cycle

    Reflex spasm of the internal anal sphincter reduces blood flow to the tear and keeps it from healing.

  • Fear of defecation

    Anticipation of pain leads to stool holding, harder stools and a self-perpetuating cycle of tearing.

  • Sentinel skin tag

    A small external tag at the distal end of a chronic fissure, often mistaken for a haemorrhoid.

  • Hypertrophied anal papilla

    A firm nodule at the proximal end of a chronic fissure, sitting just inside the anal canal at the dentate line.

  • Fibrotic edges

    Rolled, indurated edges and visible fibres of the internal sphincter in the base of a truly chronic fissure.

  • Red flag - atypical location

    A lateral, multiple or painless fissure needs review for Crohn's, HIV, tuberculosis, syphilis or anal cancer.

Treatment

How anal fissure is treated in the UK.

Soft stools and simple topical care first, then topical vasodilators, then botulinum toxin and surgery for the fissures that refuse to heal.

  • Stool softeners and fibre

    Adequate fluid, gradual fibre and an osmotic laxative such as macrogol keep stools soft and reduce tearing at each motion.

  • Warm sitz baths

    Ten to fifteen minutes in warm water two to three times a day relaxes the internal sphincter and eases pain.

  • Topical local anaesthetic

    Lidocaine ointment before defecation dulls the pain enough to break the fear and spasm cycle in acute fissures.

  • Topical GTN 0.2 to 0.4 percent

    A nitric oxide donor that relaxes the internal sphincter. Effective but often causes headaches, which limits adherence over six to eight weeks.

  • Topical diltiazem 2 percent

    A calcium-channel blocker with similar healing rates to GTN and far fewer headaches. Often the preferred first-line topical in UK practice.

  • Botulinum toxin injection

    Injected into the internal anal sphincter under anaesthesia. A short chemical relaxation lets a chronic fissure heal without permanent sphincter change.

  • Lateral internal sphincterotomy

    The surgical gold standard for refractory chronic fissure. Highly effective but carries a one to five percent risk of minor faecal incontinence.

  • Advancement flap

    A sphincter-sparing option using healthy tissue to cover the fissure. Preferred where the incontinence risk from sphincterotomy is unacceptable.

The ladder in one sentence

Soft stools and sitz baths, then diltiazem or GTN for six to eight weeks, then botulinum toxin, then lateral internal sphincterotomy - or an advancement flap where the incontinence risk is too high.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist colorectal society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or colorectal surgeon knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE Clinical Knowledge Summary. Anal fissure.

  • Association of Coloproctology of Great Britain and Ireland (ACPGBI). Guidelines on the management of anal fissure.

  • American Society of Colon and Rectal Surgeons. Clinical practice guideline for the management of anal fissures.

  • Cochrane Review. Non-surgical therapy for anal fissure.

Red flags

When anal pain needs more than fissure care.

Most fissures are manageable in primary care. These are the situations that are not, and where colorectal input is needed.

  • Change in bowel habit or weight loss

    Persistent altered bowel habit, unintentional weight loss or iron-deficiency anaemia deserves urgent colorectal review, not fissure care alone.

  • Atypical or lateral fissure

    A fissure off the midline, multiple fissures or a painless fissure suggests Crohn's disease, HIV, tuberculosis, syphilis or anal malignancy.

  • Painless anal bleeding

    Bleeding without the tearing pain of a fissure needs a different diagnosis, including haemorrhoids, polyps or cancer.

  • Perianal sepsis

    Throbbing pain, fever, swelling or a discharging tract points to an abscess or fistula, not a simple fissure. Urgent surgical review is needed.

  • Non-healing fissure at 8 weeks

    A fissure that has not healed after eight weeks of first-line care meets the definition of chronic and needs escalation on the ladder.

  • Recurrent fissures

    Repeated fissures despite good bowel habit raise the question of an underlying inflammatory bowel disease or high resting sphincter tone.

  • Postpartum fissure with incontinence

    A fissure after childbirth combined with any hint of faecal urgency or leakage needs anorectal physiology before any sphincter surgery.

  • Immunosuppression

    Fissures in HIV, transplant patients or those on biologics behave differently and often need specialist input from the outset.

  • Suspected malignancy

    An indurated, irregular or ulcerated lesion is not a fissure. Biopsy is mandatory.

Living with it

A treatable condition, with a clear ladder.

Four things that make the biggest difference day to day: soft stools, warm sitz baths, patience with topicals and knowing when to step up.

A quiet reminder

You are not alone in this.

Fissures are among the most common colorectal presentations. Modern treatment is highly effective and clinicians see this every week.

  1. 01 Bowels

    Soft, formed stools every day

    Fibre, fluid and an osmotic laxative if needed. Aim for a comfortable pass, not straining and not urgency.

  2. 02 Routine

    Warm baths and time to heal

    A sitz bath after each bowel motion and a short course of topical treatment gives the tear the best chance to close.

  3. 03 Patience

    Give topicals six to eight weeks

    GTN and diltiazem are slow. Judge them at two months, not two weeks, and swap only if side effects are intolerable.

  4. 04 Escalate

    Don't suffer a chronic fissure

    If a fissure has not healed on topicals, botulinum toxin and surgery are highly effective and safer than years of pain.

Frequently asked

Everything we get asked about anal fissure.

Quick answers on healing times, topicals, botulinum toxin and surgery.

  • What is an anal fissure?

    An anal fissure is a linear tear in the sensitive skin of the anal canal, usually caused by a hard stool. It causes a searing pain during defecation and bright red bleeding, and often triggers spasm of the internal sphincter that prevents healing.

  • How long does an anal fissure take to heal?

    Most acute fissures heal within six to eight weeks with stool softeners, fibre, hydration, warm sitz baths and topical local anaesthetic. A fissure that persists beyond eight weeks is classified as chronic and needs escalation to a topical vasodilator, botulinum toxin or surgery.

  • Are GTN and diltiazem safe to use?

    Both are widely used and safe when applied as directed for six to eight weeks. GTN commonly causes headaches, which limits adherence, so diltiazem 2 percent is often preferred first as it has similar healing rates and far fewer side effects.

  • When is surgery needed for an anal fissure?

    Surgery is reserved for chronic fissures that have not healed after a proper trial of topical treatment and botulinum toxin. Lateral internal sphincterotomy is the gold standard, with an advancement flap used when the risk of incontinence from sphincterotomy is too high.

  • Will a sphincterotomy make me incontinent?

    A lateral internal sphincterotomy carries a small risk of minor faecal incontinence, typically to flatus, in around one to five percent of patients. The risk is higher in women, in the elderly and after obstetric injury, which is why an advancement flap is offered in those groups.

  • What if my fissure is not in the usual place?

    A fissure off the posterior or anterior midline, multiple fissures, or a painless fissure is atypical and should prompt review for Crohn's disease, HIV, tuberculosis, syphilis and anal cancer. Biopsy and colonoscopy are often needed before treating the fissure itself.

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