What are the treatment options for toenail fungus?

Treatment for Toenail Fungus

Oral terbinafine 250 mg daily for 12 weeks is the first-line treatment for toenail onychomycosis, with superior efficacy compared to all other antifungal agents. 1, 2, 3, 4

Confirm Diagnosis Before Treatment

• Always obtain mycological confirmation before initiating therapy through KOH preparation, fungal culture, or nail biopsy to avoid treating non-fungal nail dystrophy 1, 2, 3
• The most common cause of treatment failure is incorrect diagnosis made on clinical grounds alone without laboratory confirmation 5

Treatment Algorithm by Disease Severity

For Most Cases: Oral Therapy Required

Oral terbinafine 250 mg once daily is the treatment of choice:

• 12 weeks for toenails (6 weeks for fingernails if affected) 1, 2, 3
• Terbinafine achieves mycological cure rates of approximately 76% compared to 38% with placebo, with high-quality evidence supporting its superiority 4
• It works by inhibiting squalene epoxidase, which is directly fungicidal against dermatophytes that cause 90-95% of nail infections 1, 2

Alternative oral option: Itraconazole

• Use when terbinafine is contraindicated or for Candida infections (where it is more effective than terbinafine with 92% cure rate) 1
• Dosing: 200 mg twice daily for 1 week per month—3 pulses (3 months total) for toenails 1
• Take with food for better absorption 1

Limited Situations for Topical Therapy Only

Topical treatments should only be used when: 6, 1

• Superficial white onychomycosis (SWO) is present
• Very early distal lateral subungual onychomycosis (DLSO) with <80% nail plate involvement and no lunula involvement
• Oral antifungals are contraindicated

Topical options (applied after filing away diseased nail):

• Amorolfine 5% nail lacquer: Apply once weekly for 12 months, achieves approximately 50% effectiveness in limited distal infections 6, 1
• Ciclopirox 8% nail lacquer: Apply daily for up to 48 weeks, achieves 34% mycological cure versus 10% with placebo 6, 7
• Ciclopirox is FDA-approved only for mild to moderate onychomycosis without lunula involvement in immunocompetent patients 7

Special Populations

Diabetic Patients

• Terbinafine is strongly preferred due to lower risk of drug interactions and hypoglycemia compared to itraconazole 1
• Treatment is particularly important as onychomycosis significantly predicts foot ulcers in diabetics 1

Immunosuppressed Patients

• Prefer terbinafine or fluconazole over itraconazole due to fewer interactions with antiretrovirals and immunosuppressants 1

Pediatric Patients

• Pulse itraconazole: 5 mg/kg/day for 1 week per month for 3 months (toenails) 1
• Terbinafine weight-based dosing: 62.5 mg/day for <20 kg, 125 mg/day for 20-40 kg, 250 mg/day for >40 kg 1
• Pediatric cure rates are higher (88-100%) than adults 1

Pre-Treatment Monitoring

• Obtain baseline liver function tests and complete blood count before starting oral antifungals 1
• Monitor liver function in patients with pre-existing abnormalities, those on continuous therapy >1 month, or taking concomitant hepatotoxic medications 1
• Itraconazole is contraindicated in heart failure 1

Common Adverse Effects

Terbinafine: 6, 4

• Gastrointestinal symptoms, headache, taste disturbances (usually temporary)
• May exacerbate psoriasis or cause subacute lupus syndrome
• Risk ratio for adverse events versus placebo: 1.13 (not significantly different) 4

Itraconazole: 4

• Headache, flu-like symptoms, nausea
• Multiple drug interactions due to cytochrome P450 inhibition 1

Critical Pitfalls to Avoid

• Never use topical therapy for extensive disease—this results in predictable failure 5
• Do not underdose or shorten treatment duration—12 full weeks of terbinafine is required for toenails 5
• Check for drug interactions before prescribing itraconazole, especially with statins, anticoagulants, and immunosuppressants 1
• Do not combine topical ciclopirox with systemic antifungals—no studies support this and it is not recommended 7

Expected Outcomes and Recurrence

• Even with optimal terbinafine therapy, expect 20-30% treatment failure rates 2, 5
• Mycological cure rates are typically 30% better than clinical cure rates because pre-existing nail dystrophy may not fully resolve 6, 2
• Recurrence rates are 40-70% after successful treatment 1, 5

Prevention strategies to reduce recurrence: 1

• Wear protective footwear in public areas
• Use absorbent and antifungal powders in shoes
• Keep nails trimmed short
• Avoid sharing nail clippers
• Consider prophylactic amorolfine nail lacquer 6

Second-Line Agents (When First-Line Options Fail or Are Contraindicated)

• Fluconazole: Less effective than terbinafine or itraconazole for dermatophytes but useful when others are not tolerated due to fewer drug interactions 1
• Griseofulvin: Only 30-40% mycological cure rates, requires 12-18 months of treatment for toenails—use only when other agents are unavailable 1, 4