What is the recommended treatment for onychomycosis (toenail fungus)?

Treatment for Toenail Fungus (Onychomycosis)

Terbinafine 250 mg daily for 12 weeks is the first-line treatment for toenail fungus (onychomycosis) due to its superior efficacy and safety profile compared to other antifungal agents. 1

Diagnosis Before Treatment

Before initiating treatment:

• Confirm diagnosis with appropriate nail specimens for laboratory testing:
  • Potassium hydroxide (KOH) preparation
  • Fungal culture
  • Nail biopsy if necessary 2

Treatment Algorithm

First-line Treatment (Dermatophyte Onychomycosis)

• Oral terbinafine 250 mg daily for 12 weeks for toenail infections 1, 2
• For fingernail infections: terbinafine 250 mg daily for 6 weeks 1

Alternative Treatment Options

1. Itraconazole (if terbinafine is contraindicated):

   • Continuous regimen: 200 mg daily for 12 weeks
   • Pulse therapy: 400 mg daily for 1 week per month for 3 months (toenails) 1

2. Fluconazole (if both terbinafine and itraconazole are contraindicated):

   • 150-450 mg once weekly for at least 6 months for toenail infections 1

3. Topical therapy (for mild cases or when oral therapy is contraindicated):

   • Ciclopirox 8% nail lacquer applied daily for up to 48 weeks 3
   • Amorolfine 5% lacquer applied once or twice weekly for 6-12 months 1

Special Populations

Diabetic Patients

• Terbinafine is preferred due to lower risk of drug interactions and hypoglycemia 1
• Itraconazole is contraindicated in patients with congestive heart failure, which is more prevalent in diabetics 1

Immunosuppressed Patients

• Terbinafine or fluconazole preferred due to fewer drug interactions with antiretrovirals 1
• Higher doses or longer treatment durations may be necessary 1

Pediatric Patients

• Terbinafine: dosed by weight (62.5 mg if <20 kg, 125 mg if 20-40 kg, 250 mg if >40 kg) 1
• Itraconazole: pulse therapy at 5 mg/kg/day for 1 week per month 1

Candida Onychomycosis

• Itraconazole is first-line for Candida infections 1
• Fluconazole is an effective alternative 1

Treatment Efficacy and Monitoring

• Expected cure rates: 70-80% for toenail infections with oral terbinafine 1
• Follow-up at 3-6 months after treatment initiation 1
• Consider additional treatment if infection persists 1

Important Considerations and Pitfalls

1. Confirm diagnosis before treatment: Many conditions can mimic onychomycosis (psoriasis, trauma, etc.) 1

2. Drug interactions:

   • Terbinafine: monitor for hepatotoxicity with baseline liver function tests 1
   • Itraconazole: contraindicated in heart failure; numerous drug interactions 1

3. Treatment failure factors:

   • Poor compliance
   • Incorrect diagnosis
   • Presence of dermatophytomas (fungal masses within the nail)
   • Reinfection from untreated tinea pedis 1

4. Continuous vs. pulse therapy: Recent evidence suggests continuous terbinafine therapy (76.7% cure rate) is superior to pulse therapy (26.7% cure rate) 4

5. Treatment duration: 12 weeks is optimal for toenail infections; shorter durations (6 weeks) have significantly lower cure rates 5, 6

The evidence strongly supports oral terbinafine as the most effective treatment for dermatophyte onychomycosis, with itraconazole as a good alternative, especially for Candida infections. Topical treatments should be reserved for mild cases or when oral therapy is contraindicated.