What is the recommended antifungal therapy for onychomycosis in children?

Antifungal Therapy for Onychomycosis in Children

First-Line Treatment Recommendations

Both terbinafine and itraconazole are equally recommended as first-line systemic treatments for dermatophyte onychomycosis in children, with terbinafine generally preferred due to its superior efficacy and safety profile. 1

Terbinafine Dosing (Weight-Based)

• < 20 kg: 62.5 mg daily 1
• 20-40 kg: 125 mg daily 1
• > 40 kg: 250 mg daily 1

Duration: 6 weeks for fingernails, 12 weeks for toenails 1

Important caveat: Terbinafine is unlicensed for pediatric use, requiring baseline liver function tests and complete blood count before initiation 1

Itraconazole Pulse Therapy

Dosing: 5 mg/kg per day for 1 week per month 1

Duration:

• 2 pulses (2 months) for fingernails 1
• 3 pulses (3 months) for toenails 1

Administration: Must be taken with food and acidic beverages for optimal absorption 1

Monitoring: Hepatic function tests recommended in patients with pre-existing liver abnormalities, those receiving continuous therapy >1 month, or with concomitant hepatotoxic drugs 1

Clinical pearl: Pediatric studies demonstrate remarkably high cure rates of 94-100% with itraconazole pulse therapy, superior to adult populations 1

Second-Line Treatment Options

Fluconazole

Use when: Terbinafine and itraconazole are contraindicated or not tolerated 1

Dosing: 3-6 mg/kg once weekly 1

Duration:

• 12-16 weeks for fingernails 1
• 18-26 weeks for toenails 1

Monitoring: Baseline liver function tests and complete blood count required; monitor LFTs in high-dose or prolonged therapy 1

Griseofulvin

Use when: Terbinafine and itraconazole are contraindicated or not tolerated 1

Dosing: 10 mg/kg per day (maximum 500 mg) for children ≥1 month 1

Administration: Must be taken with fatty food to increase absorption 1

Important limitation: No longer recommended as first-line due to long treatment duration and lower efficacy compared to terbinafine and itraconazole 1

Topical Therapy Considerations

Children respond better to topical monotherapy than adults due to thinner, faster-growing nails 2, 3

FDA-Approved Topical Options for Children

• Efinaconazole 10% solution: Approved for children ≥6 years 2
• Tavaborole 5% solution: Approved for children ≥6 years 2
• Ciclopirox 8% nail lacquer: Approved for children ≥12 years 2

Clinical approach: Topical agents can be used as monotherapy for mild distal infections or combined with systemic therapy for enhanced efficacy 1, 3

Critical Management Principles

Pre-Treatment Requirements

• Mycological confirmation mandatory before initiating therapy to avoid treating non-fungal nail dystrophies 4
• Examine parents and siblings for onychomycosis and tinea pedis, as family transmission is common 1
• Check for concomitant tinea capitis and tinea pedis in the affected child 1

Contraindications to Monitor

• Terbinafine: Hepatic impairment; can aggravate psoriasis and cause subacute lupus-like syndrome 1
• Itraconazole: Heart failure (negative inotropic effect), hepatotoxicity 1
• Fluconazole: Hepatic impairment, renal impairment 1

Common Adverse Effects

All three first-line agents share similar adverse effect profiles: headache and gastrointestinal upset 1

Terbinafine-specific: Taste disturbance (uncommon but notable) 1

Treatment Success Factors

Children achieve higher cure rates and faster response than adults due to thinner nail plates and faster nail growth 1, 3

Follow-up duration: Monitor for at least 48 weeks from treatment start to identify potential relapse 5

Prevention strategies:

• Decontaminate or replace contaminated footwear 5
• Apply antifungal powders inside shoes regularly 5
• Keep nails short and clean 5
• Avoid sharing nail clippers with infected family members 5

Algorithm for Treatment Selection

1. Confirm diagnosis with mycological examination (microscopy and culture) 4
2. For dermatophyte onychomycosis: Choose terbinafine (preferred) or itraconazole pulse therapy as first-line 1
3. For Candida onychomycosis: Use itraconazole as first-line (superior to terbinafine for yeast) 4
4. If first-line agents contraindicated: Use fluconazole or griseofulvin 1
5. Consider topical monotherapy for very distal or superficial infections, especially in younger children 2, 3
6. Consider combination therapy (systemic + topical) for enhanced efficacy and broader antifungal spectrum 1