What are the treatment options for onychomycosis?

Treatment Options for Onychomycosis

Oral terbinafine is the first-line treatment for onychomycosis, with 250mg daily for 12 weeks for toenails and 6 weeks for fingernails providing the highest cure rates and lowest relapse rates compared to other antifungal medications. 1, 2, 3

Systemic Treatment Options

First-line Therapy

• Terbinafine:
  • Dosage: 250mg once daily
  • Duration: 12 weeks for toenails, 6 weeks for fingernails
  • Efficacy: 76-81% mycological cure rate, superior to other antifungals 1, 3
  • Advantages: Fungicidal activity, low drug interaction potential, persists in nail for weeks after treatment 3
  • Before initiating: Confirm diagnosis with appropriate nail specimens (KOH preparation, fungal culture, or nail biopsy) 2
  • Monitoring: Baseline liver function tests and CBC for patients with history of alcohol consumption, liver disease, or hematological abnormalities 1

Alternative Systemic Options

• Itraconazole:

  • Dosage options:
    • Continuous: 200mg daily for 12 weeks
    • Pulse therapy: 400mg daily for 1 week per month for 3 months
  • Note: Contraindicated in congestive heart failure; more drug interactions than terbinafine 4, 1

• Fluconazole:

  • Dosage: 150-450mg once weekly
  • Duration: At least 6 months
  • Note: Not FDA-approved specifically for onychomycosis 1

Topical Treatment Options

• Indicated for:

  • Mild to moderate infections
  • Patients with contraindications to oral therapy
  • Adjunct to systemic therapy

• Options include:

  • Ciclopirox 8% nail lacquer:

    • Application: Once daily for up to 48 weeks
    • Efficacy: 34% mycological cure rate, 8% clinical cure rate 1, 5
    • Requires removal of unattached, infected nails monthly by healthcare professional 5

  • Amorolfine 5% nail lacquer:

    • First-line topical treatment for mild to moderate cases
    • Efficacy: ~50% mycological cure rate 1

  • Efinaconazole 10% solution:

    • Application: Once daily for 48 weeks
    • Efficacy: ~50% mycological cure rate, 15% complete cure rate 1

Special Populations

Pediatric Patients

• Onychomycosis is less common in children (<0.5% prevalence)
• Topical treatment often advocated due to thinner, faster-growing nail plates
• For systemic therapy:

  • Terbinafine (weight-based dosing):

    • <20kg: 62.5mg daily
    • 20-40kg: 125mg daily

    • 40kg: 250mg daily

    • Duration: 6 weeks for fingernails, 12 weeks for toenails 4, 1

  • Pulse itraconazole: 5mg/kg/day for 1 week every month (2 months for fingernails, 3 months for toenails) 4

  • Fluconazole: 3-6mg/kg once weekly (12-16 weeks for fingernails, 18-26 weeks for toenails) 4

Diabetic Patients

• Up to one-third of diabetics may have onychomycosis
• Terbinafine is preferred due to:
  • Lower risk of drug interactions
  • No risk of hypoglycemia
  • Itraconazole is contraindicated in congestive heart failure (common in diabetics) 4, 1
• Topical treatments appropriate for mild-to-moderate infections when drug interaction risk is high 4

Immunosuppressed Patients

• Higher prevalence in immunosuppressed populations
• Consider terbinafine or fluconazole over itraconazole due to fewer interactions with antiretrovirals 1

Treatment Selection Algorithm

1. Confirm diagnosis with KOH preparation, fungal culture, or nail biopsy 2
2. Assess severity and extent of infection:
   • Mild to moderate without lunula involvement → Consider topical therapy
   • Moderate to severe or with lunula involvement → Systemic therapy indicated
3. Consider patient factors:
   • Comorbidities (diabetes, heart disease, liver disease)
   • Medication interactions
   • Age (pediatric vs adult)
   • Causative organism (dermatophyte vs Candida vs non-dermatophyte mold)
4. For most adult patients with dermatophyte infection: Terbinafine 250mg daily (12 weeks for toenails, 6 weeks for fingernails) 1, 3
5. For Candida infections: Consider itraconazole as it may be more effective than terbinafine 1

Common Pitfalls and Caveats

• Misdiagnosis: Only about 50% of abnormal-appearing nails are due to onychomycosis; consider psoriasis, lichen planus, and trauma in differential diagnosis 6
• Inadequate treatment duration: Complete nail regrowth takes time; patience is required
• Failure to address predisposing factors: Treat concomitant tinea pedis
• Treatment failure causes: Poor compliance, poor absorption, immunosuppression, dermatophyte resistance, subungual dermatophytoma, zero nail growth 1
• Continuous vs pulse therapy: Recent evidence suggests continuous terbinafine regimens have superior clinical cure rates (76.67%) compared to pulse regimens (26.67%) 7