What is the recommended treatment for an anal fissure, including first‑line and second‑line options and special considerations for pregnancy and children?

Anal Fissure Treatment

For acute anal fissures, start with conservative management including fiber supplementation (25-30g daily), adequate hydration, and warm sitz baths, which heals approximately 50% of cases within 10-14 days; if this fails after 2 weeks or for chronic fissures, add compounded topical 0.3% nifedipine with 1.5% lidocaine three times daily for 6-8 weeks (achieving 95% healing rates), and reserve lateral internal sphincterotomy only for cases failing 6-8 weeks of comprehensive medical therapy. 1, 2, 3

Initial Assessment and Red Flags

Before initiating treatment, examine the fissure location by effacing the anal canal with opposing traction on the buttocks. 2

Critical red flags requiring urgent workup:

• Lateral or off-midline fissures (typical fissures occur in the posterior midline in 90% of cases; anterior in 10% of women vs 1% of men) 1, 2, 4
• Multiple fissures 1, 4
• Lack of response after 8 weeks of conservative treatment 2

These atypical presentations mandate urgent evaluation for Crohn's disease, HIV/AIDS, ulcerative colitis, tuberculosis, syphilis, or malignancy before initiating any treatment. 1, 2, 4

First-Line Conservative Management (All Acute Fissures)

Dietary and lifestyle modifications (strong recommendation): 1, 2, 3

• Increase fiber intake to 25-30g daily through diet or fiber supplementation to soften stools and minimize anal trauma 1, 2, 3
• Ensure adequate fluid intake throughout the day to prevent constipation 1, 2, 3
• Warm sitz baths 2-3 times daily to promote internal anal sphincter relaxation 1, 2, 3
• Topical analgesics (lidocaine 5%) for pain control 2, 3, 4

Expected outcome: Approximately 50% of acute anal fissures heal with these measures alone within 10-14 days. 1, 2, 3

Second-Line Pharmacologic Treatment

If conservative measures fail after 2 weeks or for chronic fissures (>8 weeks):

Preferred Option: Topical Calcium Channel Blockers

Compounded 0.3% nifedipine with 1.5% lidocaine applied three times daily for at least 6 weeks achieves 95% healing rates. 2, 3 The calcium channel blocker reduces internal anal sphincter tone by blocking slow L-type calcium channels, increasing local blood flow to the ischemic ulcer and interrupting the pain-spasm-ischemia cycle. 2, 3 Pain relief typically occurs after 14 days of treatment. 3

Alternative: Compounded 2% diltiazem cream applied twice daily for 8 weeks achieves healing rates of 48-75% without the headache side effects associated with nitroglycerin. 2

Less Preferred Option: Topical Nitrates

Topical nitroglycerin (GTN) shows only 25-50% healing rates and causes headaches in many patients, making it less preferred than calcium channel blockers. 2, 5

Alternative: Botulinum Toxin Injection

Botulinum toxin injection into the internal anal sphincter demonstrates 75-95% cure rates with low morbidity and should be considered as a viable second-line treatment option, especially in patients at risk for incontinence. 2, 5

Critical Pitfalls to Avoid

Absolutely contraindicated interventions:

• Manual anal dilatation is strongly contraindicated due to unacceptably high permanent incontinence rates of 10-30% 1, 2, 3, 4
• Hydrocortisone beyond 7 days due to risk of perianal skin thinning and atrophy, which can worsen the fissure 2, 3
• Surgery for acute fissures (except in cases of severe, intractable pain) 2, 4

Surgical Management

Lateral internal sphincterotomy (LIS) indications: 1, 2, 3

• Chronic fissures (>8 weeks) that have failed 6-8 weeks of comprehensive medical therapy (fiber supplementation, adequate hydration, warm sitz baths, AND topical calcium channel blocker therapy) 1, 2, 3
• Acute fissures with severe, intractable pain that makes conservative care intolerable 2

LIS outcomes: Healing rates >95% with recurrence rates of 1-3%, making it the gold standard for chronic fissures. 2, 5 However, it carries a small risk of minor permanent incontinence defects. 2

Special Populations

Pregnancy

While specific pregnancy data is limited in the guidelines, conservative management with fiber, hydration, and sitz baths should be prioritized. 1, 2, 3 Topical calcium channel blockers may be considered, but consultation with obstetrics is prudent before initiating pharmacologic therapy.

Children

Conservative management with fiber supplementation, adequate hydration, and warm sitz baths remains first-line treatment. 1, 2, 3 Surgical intervention should be reserved for truly refractory cases after extended medical therapy failure, given the higher priority of avoiding incontinence risk in this population.

Treatment Algorithm Summary

1. Confirm typical fissure location (posterior midline) - if atypical, stop and evaluate for underlying disease 1, 2, 4
2. Start conservative management (fiber 25-30g daily, hydration, sitz baths 2-3x daily, topical lidocaine) for all acute fissures 1, 2, 3
3. Reassess at 2 weeks - if no improvement, add compounded 0.3% nifedipine with 1.5% lidocaine three times daily 2, 3
4. Continue pharmacologic therapy for 6-8 weeks total 1, 2, 3
5. If failure after 6-8 weeks of comprehensive medical therapy, refer for lateral internal sphincterotomy 1, 2, 3