Topical Ointments for Anal Fissure

Overview

Anal fissures cause pain via a cycle of sphincter spasm -> ischemia -> impaired healing. All topical ointments aim to break this cycle by chemically relaxing the internal anal sphincter ("chemical sphincterotomy") and improving blood flow to the anoderm.

1. Glyceryl Trinitrate (GTN / Nitroglycerin) Ointment

Mechanism: Nitric oxide donor - relaxes internal anal sphincter smooth muscle, reduces resting anal pressure, and increases anodermal blood flow.

Formulation & Dose:

0.2%-0.5% ointment (NOTE: commercial preparations come as 2% - must be compounded/diluted)
Apply a small amount (about the size of a pencil eraser) directly to the fissure with a finger
3-4 times daily for 6-8 weeks
Typical Rx: "0.2% nitroglycerin ointment, Disp: 60 g, Sig: apply small amount to anal fissure 3-4x/day for 6-8 weeks"

Efficacy: Heals approximately 50% of chronic fissures

Side Effects:

Dose-related headache - the major limiting side effect; occurs in up to 20% of patients, leading to therapy cessation
If headache occurs: take aspirin 1 hour beforehand and reduce the amount applied
Do not apply with a rectal tube-tipped applicator or suppository

(Pfenninger and Fowler's Procedures for Primary Care, 3rd Ed.; Sabiston Textbook of Surgery)

2. Diltiazem Ointment (Calcium Channel Blocker)

Mechanism: Blocks voltage-gated calcium channels in smooth muscle of the internal anal sphincter, causing relaxation.

Formulation & Dose:

2% diltiazem ointment (compounded - no commercial formulation readily available)
Applied 2-3 times daily

Efficacy: Similar healing rates to GTN (~50% of chronic fissures)

Advantages over GTN:

Significantly fewer headaches
Now often preferred as first-line topical agent over nitrates

Side Effects: May cause local pruritus ani

(Roberts and Hedges' Clinical Procedures in Emergency; Sabiston Textbook of Surgery)

3. Nifedipine Gel (Calcium Channel Blocker)

Mechanism: Same as diltiazem - calcium channel blockade relaxes internal anal sphincter.

Formulation & Dose:

0.2% nifedipine gel (compounded)
Often combined with lidocaine 1.5%
Mix 10 x 20 mg nifedipine capsules in 100 mL surgical lubricant; apply to rectal area 2-4x daily
K-Y Jelly or 2% lidocaine jelly can replace surgical lubricant

Efficacy: Comparable to GTN and diltiazem

(Pfenninger and Fowler's; Rosen's Emergency Medicine)

4. Lidocaine (Lignocaine) Ointment

Mechanism: Topical local anaesthetic only - provides symptom relief but does NOT treat the underlying sphincter spasm.

Formulation & Dose:

5% lidocaine ointment
Apply on arising, at bedtime, and after bowel movements as needed

Role: Adjunct for severe pain; not a definitive treatment. Does not promote fissure healing.

(Pfenninger and Fowler's; Sabiston - referenced RCT vs hydrocortisone)

5. Topical Steroids (Hydrocortisone)

Role: Limited and short-term use only. May help reduce perianal inflammation. Not recommended for long-term use. Evidence of efficacy is weak compared to nitrates/CCBs.

Treatment Algorithm Summary

Step	Agent	Notes
Conservative (first)	High-fiber diet, sitz baths, stool softeners	Resolves most acute fissures in 4-6 weeks
First-line topical	Diltiazem 2% or GTN 0.2%-0.5%	Prefer diltiazem (fewer headaches); 6-8 weeks
Adjunct analgesia	Lidocaine 5% ointment	Symptom relief only
Second-line	Botulinum toxin injection	20-100 IU into internal sphincter; ~3 months effect
Surgical	Lateral internal sphincterotomy (LIS)	Definitive; healing 88-100%; risk of incontinence

Key Points on Application

Always apply ointment directly to the fissure with a finger - never use a rectal tube applicator or suppositories, as these worsen symptoms
Do not use silver nitrate or electrocautery on the fissure
Avoid anal dilators (risk of incontinence)
Most fissures are in the posterior midline (75-90%); atypical locations warrant workup for Crohn's disease, HIV, TB, malignancy

Recent evidence (2025): A systematic review (Aygin et al., Acta Gastroenterol Belg, 2025) evaluated both surgical and conservative approaches for anal fissure treatment - consistent with the above step-up approach favoring conservative/topical management first, with surgery reserved for refractory cases.

Sources: Pfenninger and Fowler's Procedures for Primary Care, 3rd Ed. | Sabiston Textbook of Surgery | Roberts and Hedges' Clinical Procedures in Emergency Medicine | Rosen's Emergency Medicine

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