What is the recommended treatment for fungal toenail (onychomycosis) infections?

Treatment of Fungal Toenail (Onychomycosis) Infections

Oral terbinafine is the first-line treatment for fungal toenail infections, with a recommended dosage of 250 mg daily for 12-16 weeks for toenail onychomycosis. 1, 2, 3

First-Line Treatment Options

Oral Therapy (Preferred for Most Cases)

• Terbinafine is the most effective treatment with the highest recommendation (strength A, evidence level 1+) for dermatophyte onychomycosis, which is the most common type 2, 4
• Dosage: 250 mg daily for 12-16 weeks for toenail infections 1, 3
• Terbinafine has demonstrated superior cure rates (70-80%) compared to other antifungals 5, 4
• Baseline liver function tests and complete blood count are recommended before starting treatment, particularly in patients with history of hepatotoxicity or hematological abnormalities 1, 3

Alternative Oral Options

• Itraconazole: 200 mg daily for 12 weeks continuously or as "pulse therapy" at 400 mg daily for 1 week per month for 3-4 pulses for toenails 1, 5
• Fluconazole: 150-450 mg weekly for at least 6 months for toenail infections 1, 5
• Griseofulvin: 500-1000 mg daily for 12-18 months for toenail infections, but has lower efficacy (30-40% cure rates) and is no longer a first-choice treatment 1, 4

Topical Treatment Options

Topical therapy should only be used in specific situations:

• Superficial white onychomycosis
• Very early distal lateral subungual onychomycosis
• When systemic therapy is contraindicated 2

Options include:

• Amorolfine 5% nail lacquer: Applied once or twice weekly for 6-12 months, with approximately 50% effectiveness in distal nail infections 1, 2
• Ciclopirox 8% nail lacquer: Applied once daily for up to 48 weeks, with mycological cure rates of 34% versus 10% with placebo 1, 2
• Tioconazole 28% solution: Applied twice daily for 6-12 months, with variable results (20-70% cure rates) 1, 2

Treatment Selection Algorithm

1. Confirm diagnosis with mycological examination (direct microscopy and culture) before initiating treatment 2, 5
2. Assess infection severity and type:
   • If superficial white onychomycosis or very early distal infection: Consider topical therapy
   • For all other presentations: Oral therapy is preferred 2
3. Select appropriate treatment:
   • For dermatophyte infections (most common): Terbinafine (first choice) or itraconazole
   • For Candida infections: Itraconazole is preferred
   • When oral therapy is contraindicated: Use amorolfine or ciclopirox nail lacquer 2, 6

Preventive Measures

To prevent recurrence:

• Keep nails short 5
• Wear protective footwear in public bathing facilities 1
• Apply antifungal powders to shoes and feet 1
• Wear cotton, absorbent socks 1
• Consider discarding heavily contaminated footwear or treating with antifungal solutions 1, 5
• Treat all infected family members simultaneously 1, 5

Important Caveats and Pitfalls

• Complete nail regrowth may take up to 18 months due to slow toenail growth 5
• Treatment failure rates of 20-30% are common even with the most effective agents 2, 5
• The most common cause of treatment failure is incorrect diagnosis made on clinical grounds alone without mycological confirmation 2
• Onychomycosis has high recurrence rates (40-70%), requiring preventive strategies 2, 5
• Nail appearance may not return to completely normal if there was pre-existing dystrophy 5
• Partially detached nails with dense white lesions underneath (dermatophytomas) may require nail removal for successful treatment 5