Treatment of Pediatric Onychomycosis with Concurrent Tinea Pedis
For children with toenail fungal infection (onychomycosis) and tinea pedis, systemic terbinafine is the preferred first-line treatment, dosed by body weight for 12 weeks, combined with topical antifungal therapy for the foot infection. 1, 2
Diagnostic Confirmation Required
Before initiating treatment, obtain mycological confirmation through potassium hydroxide preparation with microscopy and/or fungal culture to avoid treating non-fungal nail dystrophies 1. This step is critical because many nail abnormalities in children are not fungal in origin.
Examine the entire child and family unit: Check the affected child for concomitant tinea capitis, and examine parents and siblings for onychomycosis and tinea pedis, as family transmission is common 3, 1.
First-Line Systemic Treatment for Toenail Involvement
Terbinafine is the preferred systemic agent based on superior efficacy (88% cure rate in children aged 4-17 years) and safety profile 1, 2:
- <20 kg body weight: 62.5 mg daily
- 20-40 kg body weight: 125 mg daily
- >40 kg body weight: 250 mg daily
- Duration: 12 weeks for toenails 1, 2
Important caveat: Terbinafine is unlicensed for pediatric use, requiring baseline liver function tests and complete blood count before initiation 2.
Alternative First-Line Option: Itraconazole
If terbinafine is contraindicated or not tolerated, itraconazole demonstrates excellent efficacy (94-100% clinical cure rate in children aged 3-14 years) 3, 1:
Itraconazole is specifically preferred if Candida species are identified as the causative organism due to broader antimicrobial coverage 1.
Concurrent Tinea Pedis Management
Topical antifungal therapy is essential for the foot infection and should be used in combination with systemic treatment for the nails 3:
- Terbinafine 1% cream: Apply twice daily for 1 week (superior to 4 weeks of clotrimazole with 93.5% mycological cure rate) 4, 5, 6
- Alternative topical agents: Clotrimazole, ciclopirox, or amorolfine can be used 3
The combination approach provides antimicrobial synergy, wider antifungal spectrum, increased cure rates, and suppression of resistant mutants 3.
Why Children Respond Better Than Adults
Children achieve higher cure rates and faster response due to thinner nail plates and faster nail growth 2, 7. This physiological advantage makes treatment more successful in pediatric populations compared to adults.
Prevention Strategies to Prevent Relapse
Implement these measures concurrently with treatment 1, 2:
- Decontaminate or replace contaminated footwear
- Apply antifungal powders inside shoes regularly
- Keep nails short and clean
- Avoid sharing nail clippers with infected family members
Second-Line Options
If both terbinafine and itraconazole are contraindicated or not tolerated 2:
- Fluconazole: 3-6 mg/kg once weekly for 18-26 weeks for toenails
- Griseofulvin: 10 mg/kg per day for at least 6 months for toenails (though less effective than newer agents) 2, 8
Monitoring and Follow-Up
Monitor for at least 48 weeks from treatment start to identify potential relapse 2. Continue medication until the infecting organism is completely eradicated as indicated by clinical or laboratory examination, as clinical relapse will occur if treatment is stopped prematurely 8.
Critical Pitfall to Avoid
Do not use topical therapy alone for nail involvement in children. While topical agents (efinaconazole 10%, tavaborole 5%, ciclopirox 8%) are FDA-approved for pediatric onychomycosis, there are no clinical trials demonstrating efficacy as monotherapy in pediatric populations 1, 7. Topical therapy should only be used as adjunctive treatment with systemic agents.