Anal fissure: treatment, ointment safety and when to seek help

An anal fissure is a tear at the anal opening that can make bowel movements intensely painful. Many recent fissures settle with treatment that reduces repeated stool-related injury; persistent fissures may need prescribed muscle-relaxing ointment or specialist procedures. The priority is confirming the cause, keeping bowel movements manageable and balancing healing against treatment harms. This guide has moderate confidence in the clinical pathway, but makes no independent claim that a particular ointment, supplement or procedure is best for every patient. NHS overview

Table of contents

• Evidence summary
• What is an anal fissure?
• How it works
• The evidence-based treatments
• Supplement and lifestyle evidence
• What works and what does not
• Risks and side effects
• Important interactions
• Who needs special assessment
• Clinician-led treatment and use
• Animal and in-vitro evidence
• Funding and source roles
• Frequently asked questions
• Sources and funding notes

Evidence summary

Clinical guidance, human outcome research and funding independence answer different questions. The guidance below explains care; it does not independently reproduce the trials behind a medicine or supplement.

What is an anal fissure?

A fissure is a break in the lining of the anal canal. It differs from a haemorrhoid, which involves swollen vascular tissue, and from an abscess, which is an infection. A person may have more than one problem, so noticing a lump or blood cannot establish the diagnosis. Hard stool, frequent diarrhoea and childbirth can be relevant triggers. A clinician can often see the tear during a careful examination. If pain makes an adequate examination impossible, further assessment under anaesthesia may be discussed. Assessment pathway

Specialist guidance describes acute symptoms as lasting less than six weeks. Multiple tears or tears away from the usual midline need broader assessment for underlying disease. An unusual appearance is a reason to investigate, not a diagnosis in itself. ASCRS guideline

How it works

Passing stool can repeatedly stretch an injured area. Pain may lead someone to delay bowel movements, allowing constipation to become harder to manage. Persistent sphincter tension can impair local blood supply. A useful treatment plan therefore considers stool consistency as well as muscle tension, rather than trying to numb pain indefinitely. Clinical mechanism

Topical diltiazem is used to relax the muscle around the anus and reduce pressure. The Guy’s and St Thomas’ leaflet explains its local use and notes that the cream is an unlicensed formulation in the UK, although oral diltiazem has other licensed indications. Unlicensed prescribing requires an explanation of the rationale and safety plan; it does not mean that a cream is interchangeable with tablets used for blood pressure. Diltiazem patient information

The evidence-based treatments

First care commonly addresses constipation or diarrhoea, rather than assuming everyone needs the same laxative. A clinician may recommend a stool-softening treatment when constipation is part of the problem. Prescription cream may be offered for a fissure that is not settling, followed by specialist review if symptoms continue. The review should ask whether the original diagnosis still fits and whether treatment was tolerable, rather than extending a prescription without reassessment. NHS treatment pathway

Specialist options include injection of botulinum toxin and an operation called lateral internal sphincterotomy. The injection temporarily relaxes the muscle; the operation divides part of it. These are distinct decisions with different recovery and bowel-control implications. The hospital leaflet describes botulinum treatment for fissures as unlicensed in the UK. Consent should cover that status as well as likely benefit, alternatives and possible harm. The procedure, anaesthetic and day-case arrangements depend on the treating service and patient. Hospital procedure information

Supplement and lifestyle evidence

Dietary fibre or a bulk-forming fibre product can be relevant when hard stool is contributing to injury. It is not suitable for every bowel problem. Ispaghula husk needs review in someone with swallowing difficulty, suspected bowel blockage or abdominal pain with nausea or vomiting. Increasing fibre without checking those symptoms can be unsafe. The aim is a manageable bowel movement, not forcing a fixed supplement amount on everyone. Fibre suitability

Gentle local care and a warm bath can ease discomfort. Avoid fragranced products and forceful wiping around a painful area. These practical measures support comfort, but should not be described as proven substitutes for examining persistent pain. This review did not establish financially cleared human evidence that probiotics, collagen, herbal creams or a “gut repair” mixture heal fissures. Products sold for general gut health should not inherit a fissure-healing claim simply because constipation is sometimes involved. NHS local care guidance

What works and what does not

A plan is more useful when it has an observable goal: less pain, easier bowel movements and a tear that the clinician considers healed. Pain relief alone cannot establish that every cause of bleeding has been excluded. A licensed UK nitrate product has an indication for pain from chronic fissures; that label is not a general guarantee of healing. This guide uses the label to understand that boundary and its safety warnings, without counting company evidence as independent proof of benefit. Prescribing indication

Comparing procedures requires more than asking which one relaxes the muscle most strongly. Weakening the sphincter can affect control of gas or stool, temporarily or permanently. That makes informed consent central to the decision. Ask which outcome matters most, how it will be assessed and what happens if symptoms recur. A colorectal specialist can relate those questions to the examination and available alternatives. This review does not turn pooled healing percentages into a conflict-cleared ranking. Procedure consent and bowel control

Risks and side effects

With nitrate ointment, headache can be severe; dizziness and low blood pressure can also occur. The patient leaflet advises avoiding driving or machinery while affected. Skin reactions and formulation ingredients matter too. Paraffin-containing ointment on clothing or bedding creates a fire hazard around smoking or naked flames. These warnings apply to the identified product, and are included as primary safety information from a commercial label. They do not certify efficacy or make other formulations identical. Product safety leaflet

Severe anal pain with fever or shivering, or constant throbbing pain with pus, needs prompt assessment for infection. Black or dark-red stool also needs urgent review. Continuous bleeding or a large amount of blood or clots is an emergency. Use local urgent-care services; do not wait for a fissure cream to work. A small amount of bright blood may fit a fissure, but that pattern is not permission to ignore recurrent bleeding. Urgent warning signs

Important interactions

Glyceryl trinitrate ointment must not be combined with phosphodiesterase-5 medicines such as sildenafil, tadalafil or vardenafil, or with other nitrate/nitric-oxide-donor products including “poppers”, because of potentially dangerous blood-pressure effects. Blood-pressure medicines and alcohol require review too. A pharmacist should check the full list, including medicines used occasionally, before treatment starts. Do not improvise a supposedly safe interval between interacting products. Primary contraindication and interaction information

Bulk-forming fibre can affect absorption of other medicines. Examples requiring pharmacist advice include lithium, digoxin, carbamazepine, diabetes treatments and mesalazine. Codeine can also worsen constipation. Give the pharmacist the exact product, all prescriptions and supplements, and the intended schedule; they can determine whether separation or another approach is needed. No universal timing rule in this article replaces that review. NHS fibre interaction information

Who needs special assessment

Existing leakage, sphincter or obstetric injury, prior anorectal surgery and inflammatory bowel disease change assessment before sphincter-dividing surgery. Describe bowel-control symptoms before consent, even if that conversation feels uncomfortable. The appropriate decision cannot be made from the word “fissure” alone. Specialist selection criteria

Pregnancy, breastfeeding and childhood change medicine decisions. The identified Rectogesic patient leaflet advises against use during pregnancy or breastfeeding and says it is unsuitable under age 18. Those restrictions concern this product, not a ban on seeking care for a fissure. Diltiazem cream also needs review for pregnancy, breastfeeding, heart problems, blood-pressure treatment and use of other diltiazem products. Ask the appropriate maternity, paediatric or prescribing team for an alternative plan. Nitrate leaflet; Diltiazem precautions

Clinician-led treatment and use

Before starting treatment, agree which problem is being treated, how to use the actual formulation and when to return if it fails. Bring the packaging to the pharmacist if instructions are unclear. Different creams, strengths and prescriptions have different directions; this article does not supply a personal dose, application depth or duration. Do not share a prescription with someone who has similar symptoms. Contact the prescriber if adverse effects prevent using the treatment as intended. Prescribed use and review

After a procedure, follow the team’s wound-care and bowel-management instructions. Gentle washing and avoiding irritating soaps are part of the hospital’s recovery advice. Arrange support after anaesthesia as instructed, and ask when usual activities can resume. Some bleeding can occur after surgery, but persistent bleeding, fever or feeling generally unwell requires contact with the treating service or urgent care. A recovery leaflet describes a care pathway; it cannot predict one patient’s recovery time. Post-operative recovery guidance

Animal and in-vitro evidence

Laboratory observations about nitric oxide, smooth-muscle relaxation, wound repair or microbial products can suggest mechanisms. They cannot determine whether a person’s tear will heal, whether the pain has another cause, or whether an intervention will preserve continence. Animal and cell findings were excluded from the human treatment verdict here. No supplement earns a clinical recommendation from an appealing wound-healing mechanism alone. An independent benefit claim would need relevant human outcomes and traceable trial financing, alongside safety and applicability.

Funding and source roles

This is a clinician-guidance article, not a financially cleared head-to-head treatment review. National NHS information is public institutional context. Guy’s and St Thomas’ is separately assessed using its own accounts; three older fissure leaflets have passed their scheduled review dates. The ASCRS disclosures are separated from its underlying trial evidence. Grünenthal’s medicine labels are commercial Tier 4 sources used only for indication, contraindications and harms. An undisclosed payment is marked unknown rather than silently treated as absent.

Frequently asked questions

Is a fissure the same as piles?

No. Their anatomy and treatment differ, although both can cause fresh blood. An examination helps distinguish them and identify coexisting problems. Fissure assessment

Should I keep treating bleeding at home?

Persistent or recurrent bleeding needs assessment. Heavy ongoing bleeding is an emergency; fever with severe anal pain also needs urgent care. NHS warning signs

Does an unlicensed cream mean it is a supplement?

No. Diltiazem cream is a prescribed medicine with a specific UK licensing status and safety plan. It is not an invitation to make a cream from oral tablets. Formulation information

Can an operation cause leakage?

Bowel-control harm is a material consent issue for muscle-relaxing or muscle-dividing procedures. Discuss existing symptoms and previous injury before choosing a procedure. Procedure consent context

Sources and funding notes

Original guideline disclosures, national public accounts, provider accounts and commercial labels were checked separately. The society’s large annual report was available through indexed official text only; no undisclosed full-account review is implied. Older provider leaflets are marked explicitly. Source roles determine what a citation can establish: a commercial safety warning is not independent efficacy evidence. Medicine-label text is February 2024; the diltiazem patient leaflet is April 2026. No animal, in-vitro or sponsored efficacy claim determines the independent verdict.

1. NHS: anal fissure — Definition, common triggers, examination and escalation
2. NHS: anal pain — Differential diagnosis and urgent bleeding/infection signs
3. Guy’s and St Thomas’: fissure treatment overview — Assessment and treatment pathway
4. Guy’s and St Thomas’: fissure surgery — Procedure choices, anaesthesia and UK licensing context
5. Guy’s and St Thomas’: recovery after fissure surgery — Wound care, recovery and post-operative warning signs
6. Guy’s and St Thomas’: diltiazem cream — Topical medicine safety and unlicensed UK formulation
7. ASCRS: 2023 anal fissure clinical guideline — Clinical context for chronic and atypical fissures and procedure selection; no independent comparative efficacy estimate
8. Rectogesic: UK prescribing information — Commercial primary label for contraindications and indication, not independent efficacy
9. Rectogesic: patient leaflet — Commercial primary safety instructions, formulation and age/pregnancy cautions
10. NHS: who can take ispaghula husk — Bulk-forming fibre suitability and obstruction/swallowing cautions
11. NHS: ispaghula interactions — Medicine absorption and pharmacist review
12. Grünenthal: corporate profile and legal identity — Financial origin and country of the commercial medicine-label source

Educational information reviewed 4 October 2026. This guide supports an informed clinical discussion; it does not diagnose an individual or provide a personal treatment regimen.