What is the treatment for onychomycosis (fungal infection of the nail) of the foot?

Treatment of Onychomycosis of the Foot

Terbinafine 250 mg daily for 12 weeks is the first-line treatment for onychomycosis of the foot, with itraconazole as the next best alternative. 1

Diagnosis Confirmation

Before initiating treatment:

• Obtain nail specimens for laboratory testing (KOH preparation, fungal culture, or nail biopsy) 2
• Confirm diagnosis as approximately 50% of nail dystrophies are not fungal in origin 3
• Target specimen collection from the most affected areas of the nail

Treatment Algorithm

First-line Treatment (Dermatophyte Infections - Most Common)

• Oral terbinafine 250 mg daily for 12 weeks 1, 2
  • Most effective agent for dermatophyte onychomycosis
  • Truly fungicidal with very low MIC (minimum inhibitory concentration)
  • Expected cure rates: 70-80% for toenail infections 1

Alternative Systemic Treatments

• Itraconazole:

  • Option 1: 200 mg daily for 12 weeks continuously
  • Option 2: Pulse therapy - 400 mg daily for 1 week per month for 3 months 1
  • Preferred for Candida infections of the nail 1

• Fluconazole (off-label):

  • 200-300 mg once weekly for 6 months for toenail infections 4
  • Lower efficacy than terbinafine for dermatophytes but may be considered when terbinafine is contraindicated

Topical Treatments (Limited Role)

• Appropriate only for:

  • Very distal infections
  • Superficial white onychomycosis (SWO)
  • Cases where systemic therapy is contraindicated 1

• Ciclopirox 8% nail lacquer:

  • Apply daily as part of a comprehensive management program
  • Requires monthly removal of unattached, infected nail by a healthcare professional 5
  • Significantly less effective than oral therapy

Management of Treatment Failure

If treatment fails after a complete course:

1. Evaluate for causes:

   • Poor compliance
   • Poor drug absorption
   • Immunosuppression
   • Dermatophyte resistance
   • Zero nail growth
   • Subungual dermatophytoma (most common cause) 1

2. Consider:

   • Alternative antifungal agent
   • Partial nail removal in combination with antifungal therapy
   • Complete nail avulsion for resistant cases 1

Prevention of Recurrence

Onychomycosis has high recurrence rates (40-70%), making preventive measures crucial:

• Discard contaminated footwear when possible
• Apply antifungal powders inside shoes
• Wear protective footwear in public bathing facilities and gyms
• Keep nails short and trimmed
• Wear cotton absorbent socks
• Consider prophylactic use of topical antifungals after successful treatment 6, 7

Important Caveats

• Complete cure may take 6-12 months due to slow nail growth
• Treat all infected family members simultaneously to prevent reinfection cycles
• Onychomycosis should not be considered a trivial disease, especially in elderly or diabetic patients where it can lead to complications like cellulitis 1, 6
• Mycological cure rates are typically about 30% better than clinical cure rates, as nails may have been dystrophic prior to infection 1