What is the recommended treatment for onychomycosis (fungal infection of the nails) of the fingernails?

Treatment for Onychomycosis of Fingernails

Oral terbinafine 250 mg daily for 6 weeks is the recommended first-line treatment for onychomycosis of fingernails due to its superior efficacy, shorter treatment duration, and established safety profile. 1, 2

Treatment Algorithm

First-line Treatment:

• Oral terbinafine 250 mg daily for 6 weeks 1, 2
  • Fungicidal action with high cure rates (approximately 80%)
  • Shorter treatment duration compared to alternatives
  • FDA approved for fingernail onychomycosis

Alternative Systemic Options:

• Itraconazole pulse therapy: 200 mg twice daily for 1 week per month × 2 pulses 1

  • Consider for Candida infections or when terbinafine is contraindicated
  • Less effective than terbinafine for dermatophyte infections
  • More drug interactions to consider

• Griseofulvin: 500-1000 mg daily for 6-9 months 1

  • Only systemic option licensed for children
  • Lower efficacy (30-40% cure rates)
  • Higher relapse rates
  • Longer treatment duration

Topical Options (for mild cases only):

• Amorolfine 5% nail lacquer: Applied once or twice weekly for 6-12 months 1

  • For superficial white onychomycosis (SWO) or early distal lateral subungual onychomycosis (DLSO)
  • Only when <80% of nail plate affected and no lunula involvement
  • Approximately 50% effective in fingernail infections

• Ciclopirox 8% nail lacquer: Applied once daily for up to 24 weeks 1, 3

  • For mild to moderate onychomycosis without lunula involvement
  • Requires monthly removal of unattached infected nail
  • Lower cure rates than amorolfine

Evidence Strength and Considerations

Terbinafine has the strongest evidence support (Level A-I) compared to other treatments 1. It demonstrates superior mycological and clinical cure rates while requiring shorter treatment duration than alternatives. Its fungicidal action is particularly effective against dermatophytes, which are the most common cause of onychomycosis 4.

Systemic therapy is consistently more successful than topical treatment for onychomycosis 1. Topical treatments should be reserved for:

• Very early or superficial infections
• Cases where systemic therapy is contraindicated
• Patients with fewer than 3 nails affected
• No matrix involvement

Important Clinical Considerations

Before Starting Treatment:

• Confirm diagnosis with appropriate nail specimens (KOH preparation, fungal culture, or nail biopsy) 2
• Assess severity, extent of involvement, and causative organism
• Review patient's medication list for potential drug interactions

Drug Interaction Precautions:

• Terbinafine: Monitor for interactions with medications metabolized by CYP2D6 (certain antidepressants, beta-blockers) 4, 5
• Itraconazole: Significant interactions with medications metabolized by CYP3A4 (statins, antihistamines, anticoagulants) 1

Monitoring:

• For terbinafine: Be aware of rare but serious adverse reactions including liver toxicity and skin reactions
• For all treatments: Assess clinical response at follow-up visits

Adjunctive Measures:

• Nail trimming and debridement improve treatment response 5
• Disinfect shoes and avoid walking barefoot in public places to prevent reinfection

Treatment Outcomes

Even with optimal treatment, patients should be informed that:

• Complete clinical cure rates are typically lower than mycological cure rates (by approximately 30%) 1
• Relapse rates are approximately 25% 5
• Fingernail infections generally respond better and faster than toenail infections

The impact of onychomycosis on quality of life should not be underestimated, as it can cause pain, discomfort, and physical impairment 5. Successful treatment significantly improves these outcomes, justifying the need for effective therapy.