How to treat onychomycosis?

Treatment of Onychomycosis

Oral terbinafine (250mg daily for 6 weeks for fingernails and 12-16 weeks for toenails) is the first-line treatment for onychomycosis due to its superior efficacy and relatively low risk of side effects. 1

Diagnosis Confirmation

Before initiating treatment:

• Obtain appropriate nail specimens for laboratory testing (KOH preparation, fungal culture, or nail biopsy) to confirm the diagnosis 2
• Assess the extent of nail involvement and type of onychomycosis

Treatment Algorithm

First-line Therapy:

1. Systemic Therapy (preferred for most cases):

   • Terbinafine: 250mg daily for 6 weeks (fingernails) or 12-16 weeks (toenails) 1

     • Highest efficacy with complete cure rates of 38% and mycological cure rates of 70% 3
     • FDA-approved for onychomycosis 2
     • Continuous dosing is significantly more effective than pulse dosing (76.67% vs 26.67% clinical cure rate) 4

   • Alternative oral options:

     • Itraconazole: 200mg daily for 12 weeks or pulse therapy (200mg twice daily for 1 week per month) 1

       • Lower efficacy than terbinafine (14% complete cure, 54% mycological cure) 3
       • Contraindicated in congestive heart failure 1
       • May be more effective for Candida onychomycosis 1

     • Fluconazole: 150-450mg once weekly for at least 6 months 1

       • Not FDA-approved for onychomycosis but used off-label 5

2. Topical Therapy (for mild cases or when systemic therapy is contraindicated):

   • Ciclopirox 8% nail lacquer: Apply daily to affected nails 1, 6

     • Requires monthly removal of unattached, infected nail by healthcare professional 6
     • Mycological cure rates of 34% 1
     • FDA-approved for mild to moderate onychomycosis without lunula involvement 6

   • Other effective topical options:

     • Efinaconazole 10% solution: Mycological cure rates of 50% 1
     • Amorolfine 5% nail lacquer: ~50% efficacy in distal nail infections 1
     • Tavaborole 5% solution: FDA-approved with more favorable safety profile 5

Special Populations

• Diabetic patients: Terbinafine preferred due to lower risk of drug interactions 1
• Immunosuppressed patients: Consider topical options when systemic therapy is contraindicated 1
• Pediatric patients: Terbinafine dosing based on weight 1
• Candida onychomycosis: Itraconazole may be more effective than terbinafine 1

Monitoring and Safety

• Baseline liver function tests and complete blood count recommended for:
  • Patients with history of heavy alcohol consumption
  • Pre-existing liver disease
  • Hepatitis
  • Hematological abnormalities 1
• Re-evaluate 3-6 months after treatment initiation 1
• Monitor for drug interactions, especially with terbinafine in combination with:
  • Tricyclic antidepressants
  • Selective serotonin reuptake inhibitors
  • Atypical antipsychotics
  • Beta blockers
  • Tamoxifen 7

Treatment Challenges and Considerations

• High recurrence rates: 40-70% even with established treatments 1

• Reasons for treatment failure:

  • Poor compliance
  • Poor absorption
  • Immunosuppression
  • Dermatophyte resistance
  • Subungual dermatophytoma
  • Zero nail growth 1

• Management of treatment failure:

  • Partial nail removal plus antifungal therapy
  • Alternative antifungal drug
  • Complete nail avulsion combined with antifungal therapy 1

Prevention Strategies

• Keep nails short
• Avoid sharing nail clippers
• Wear protective footwear in public areas
• Apply antifungal powders in shoes and on feet
• Wear cotton, absorbent socks
• Treat concomitant fungal infections 1

Emerging Treatments

Newer agents showing promise in clinical trials:

• Posaconazole: 200mg/day × 24 weeks (54.1% complete cure, 70.3% mycological cure) 3
• Fosravuconazole: 100mg/day × 12 weeks (59.4% complete cure, 82.0% mycological cure) 3
• Oteseconazole: 300mg/day × 2 weeks, then 300mg/week × 10 weeks (45% complete cure, 70% mycological cure) 3

These newer agents may provide alternatives for patients with treatment-resistant infections or those who cannot tolerate first-line therapies.