What are the treatment options for onychomycosis (fungal nail infection)?

Treatment for Fungal Nail Infection

Oral terbinafine 250 mg daily is the first-line treatment for most fungal nail infections: 6 weeks for fingernails and 12 weeks for toenails. 1, 2

When to Use Oral vs. Topical Therapy

Oral therapy is strongly preferred and almost always more successful than topical treatment. 3, 1

Use Topical Therapy ONLY When:

• Superficial white onychomycosis (SWO) affecting only the nail surface 3, 1
• Very early distal infection with <80% nail plate involvement AND no lunula (half-moon) involvement 3, 1
• Oral antifungals are contraindicated due to drug interactions or medical conditions 3, 1

Use Oral Therapy For:

• All other presentations beyond the limited criteria above 1
• Any infection involving the lunula 3
• More than 80% nail plate involvement 3
• Multiple nail involvement (>3 nails affected) 4

Oral Treatment Options

First-Line: Terbinafine (Highest Quality Evidence)

• Terbinafine 250 mg once daily 1, 2
• Duration: 6 weeks for fingernails, 12 weeks for toenails 1
• Strength of recommendation: A (highest level), Evidence level: 1+ 1
• Most effective for dermatophyte infections (the most common cause) 1, 4

Alternative: Itraconazole

• Particularly effective for Candida (yeast) infections 3, 1
• Can be given as pulse therapy: 5 mg/kg per day for 1 week each month 3
• Caution: Multiple drug interactions, especially with antiretrovirals, immunosuppressants, and cardiac medications 3, 1
• Contraindicated in congestive heart failure due to negative inotropic effects 3

Topical Treatment Options (Limited Role)

Amorolfine 5% Nail Lacquer

• Apply once or twice weekly for 6-12 months 3
• Approximately 50% effectiveness in distal nail infections 3
• File down diseased nail before each application 3
• Once-weekly application is as effective as twice-weekly 3

Ciclopirox 8% Nail Lacquer

• Apply once daily for up to 48 weeks 3, 5
• Mycological cure: 34% vs. 10% with placebo 3, 5
• Clinical cure: only 8% vs. 1% with placebo 3, 5
• Lower cure rates than amorolfine 3
• Must be used with monthly professional nail debridement 5

Tioconazole 28% Solution

• Variable results: 20-70% cure rates 3, 1
• Not commonly recommended due to inconsistent efficacy 3

Special Populations

Diabetic Patients

• Terbinafine is strongly preferred over itraconazole 3, 1
• Rationale: Low risk of drug interactions and hypoglycemia 3, 1
• Important: Onychomycosis significantly increases risk of foot ulcers in diabetics 3

Immunosuppressed Patients (HIV, Transplant Recipients)

• Terbinafine or fluconazole preferred over itraconazole 3, 1
• Rationale: Reduced drug interactions with antiretrovirals and immunosuppressants 3, 1

Pediatric Patients

• Pulse itraconazole: 5 mg/kg per day for 1 week monthly, 2 months for fingernails, 3 months for toenails 3
• Terbinafine daily: 62.5 mg if <20 kg, 125 mg if 20-40 kg, 250 mg if >40 kg 3
• Higher cure rates than adults: 88-100% in studies 3, 1

Critical Pitfalls to Avoid

Most Common Cause of Treatment Failure

Incorrect diagnosis made on clinical grounds alone without mycological confirmation 3, 1

• Always confirm diagnosis with KOH preparation, fungal culture, or nail biopsy before treatment 3, 2
• Do not treat based on appearance alone 3, 1

Other Common Mistakes

• Using topical therapy for extensive disease results in predictable failure 1
• Underdosing or insufficient treatment duration leads to poor outcomes 1
• Not considering drug interactions with itraconazole, particularly in patients on multiple medications 1
• Expecting complete clinical cure: Mycological cure rates are typically 30% higher than clinical cure rates 3

Expected Outcomes and Recurrence

Realistic Expectations

• Treatment failure rates of 20-30% even with the most effective agents 1
• Mycological cure does not always equal cosmetically normal nails if pre-existing dystrophy was present 3
• High recurrence rates: 40-70% requiring preventive strategies 1

Patient Satisfaction

• Patient satisfaction typically mirrors mycological cure rates, not clinical appearance scores 3
• Eradication of the organism usually restores nails to their pre-infection state 3

Treatment Algorithm Summary

1. Confirm diagnosis with mycology (KOH, culture, or biopsy) 3, 1, 2
2. Assess infection severity and extent 1
3. If superficial white or very early distal (<80% involvement, no lunula): Consider topical amorolfine 5% or ciclopirox 8% 3, 1
4. For all other cases: Oral terbinafine 250 mg daily (6 weeks fingernails, 12 weeks toenails) 1, 2
5. If Candida infection confirmed: Consider itraconazole instead 3, 1
6. Special populations: Adjust based on comorbidities and drug interactions 3, 1