What is the recommended treatment for an anal fissure?

Treatment of Anal Fissure

For acute anal fissures, start with conservative management including increased fiber/water intake, sitz baths, and topical anesthetics; if no improvement after 2 weeks, add topical calcium channel blockers (diltiazem or nifedipine) which are superior to nitroglycerin with 65-95% healing rates and fewer side effects. 1, 2

Initial Assessment and Red Flags

Before initiating treatment, determine if the fissure is typical or atypical:

• Typical fissures are located in the posterior midline (90% of cases) and can proceed directly to treatment 1, 3
• Atypical fissures (lateral location, multiple fissures, or anterior in men) require urgent evaluation for Crohn's disease, HIV/AIDS, tuberculosis, syphilis, inflammatory bowel disease, or malignancy before any treatment 1, 3
• Perform endoscopy, CT, MRI, or endoanal ultrasound only if you suspect these underlying conditions 1

First-Line Conservative Management (Weeks 1-2)

All patients should begin with conservative measures, which heal approximately 50% of acute fissures within 10-14 days: 1, 2, 4

• Dietary modifications: Increase fiber intake through diet or supplements 1, 2
• Hydration: Adequate fluid intake to soften stools 1, 2
• Stool softeners: Use bulk-forming laxatives if dietary changes are insufficient 1
• Sitz baths: Warm water baths to relax the internal anal sphincter 1, 2
• Topical anesthetics: Lidocaine 5% applied 3 times daily for pain control, which reduces reflex sphincter spasm and promotes healing 2
• Systemic analgesics: Paracetamol or ibuprofen for severe pain 2

Special Consideration for Infected Fissures

If there is evidence of infection or poor genital hygiene, add metronidazole cream combined with lidocaine 5% three times daily, which achieves 86% healing rates versus 56% with lidocaine alone 2

Second-Line Medical Treatment (After Week 2)

If the fissure persists beyond 2 weeks despite conservative treatment, add topical calcium channel blockers: 2

• Preferred agents: Diltiazem or nifedipine with healing rates of 65-95% 2, 5
• Why calcium channel blockers over nitroglycerin: They have comparable or superior efficacy with significantly fewer side effects, particularly avoiding the moderate-to-severe headaches that occur with nitroglycerin 1, 2, 6
• Nitroglycerin limitations: Healing rates are only 25-50%, and headaches frequently limit compliance 1, 2

Third-Line Treatment: Botulinum Toxin

For fissures that fail topical therapy after 6-8 weeks, botulinum toxin injection is highly effective: 1

• Efficacy: 75-95% healing rates, superior to nitroglycerin (96% vs 60% in head-to-head comparison) 1, 6
• Safety profile: Minimal side effects, no permanent sphincter damage, and no fecal incontinence reported 6
• Advantages over surgery: Avoids the risk of permanent incontinence while achieving near-surgical cure rates 7, 6
• Limitation: Optimal injection location (internal vs external sphincter) remains controversial, and long-term relapse rates require further study 1

Surgical Treatment: Lateral Internal Sphincterotomy (LIS)

Reserve surgery for chronic fissures failing 8+ weeks of optimal medical management, or for acute fissures with intolerable pain requiring immediate action: 1

• Efficacy: Healing rates exceed 95% with only 1-3% recurrence 1, 7
• Major caveat: Risk of permanent minor sphincter impairment and fecal incontinence (temporary up to 30%, permanent up to 10%) 2, 7
• Contraindications: Do not perform in acute phase, in patients with compromised sphincter function, or when continence is already questionable 1, 2

Critical Contraindications

Manual anal dilatation is absolutely contraindicated due to unacceptably high rates of permanent incontinence (up to 10%) 2, 3, 8

Treatment Algorithm Summary

1. Weeks 0-2: Conservative care (fiber, fluids, sitz baths, topical lidocaine) 1, 2
2. Week 2+: Add topical calcium channel blockers if no improvement 2
3. Week 6-8+: Consider botulinum toxin injection if topical therapy fails 1, 6
4. Week 8+: Consider LIS only for refractory cases, weighing incontinence risk 1, 7

Key principle: Prioritize treatments that temporarily reduce sphincter tone without permanent damage, reserving surgery for truly refractory cases where the benefit of rapid healing outweighs the risk of permanent incontinence. 1