What is the recommended treatment for a patient with onychomycosis (fungal nail infection) of the hands?

Treatment of Onychomycosis of the Hands

For fungal nail infections of the fingernails, oral terbinafine 250 mg once daily for 6 weeks is the first-line treatment, with topical therapy reserved only for very limited disease. 1, 2

Treatment Algorithm

Step 1: Confirm the Diagnosis

• Obtain nail specimens for laboratory testing (KOH preparation, fungal culture, or nail biopsy) before initiating treatment to confirm onychomycosis 1, 2
• The most common cause of treatment failure is incorrect diagnosis made on clinical grounds alone without mycological confirmation 1

Step 2: Assess Disease Severity

Use topical therapy ONLY if ALL of the following criteria are met:

• Superficial white onychomycosis (SWO) affecting only the nail surface 3, 1
• Very early distal lateral subungual onychomycosis with less than 80% nail plate involvement 3, 1
• No lunula (half-moon) involvement 3, 4
• Systemic antifungals are contraindicated 3, 1

Use oral therapy for:

• Any infection beyond the above criteria 1
• Most cases of fingernail onychomycosis 1

Step 3: Select Appropriate Treatment

For Oral Therapy (First-Line)

• Terbinafine 250 mg once daily for 6 weeks for fingernails (strength A, evidence level 1+) 1, 2
• This achieves significantly better cure rates than placebo, with high-quality evidence supporting clinical cure (RR 6.00) and mycological cure (RR 4.53) 5
• Terbinafine is more effective than azoles for achieving both clinical cure (RR 0.82) and mycological cure (RR 0.77) 5

Alternative Oral Therapy

• Itraconazole is particularly effective for Candida infections of the fingernails 1
• Consider itraconazole when the causative organism is yeast rather than dermatophyte 6

For Topical Therapy (Limited Disease Only)

When oral therapy is contraindicated and disease meets criteria above:

• Amorolfine 5% nail lacquer applied once or twice weekly for 6-12 months, achieving approximately 50% effectiveness in fingernail onychomycosis 3
• Ciclopirox 8% nail lacquer applied once daily for up to 48 weeks, achieving 34% mycological cure versus 10% with placebo 3, 4
• Efinaconazole 10% topical solution applied once daily, achieving mycological cure rates approaching 50% after 48 weeks 3

Critical caveat: Topical therapy must be combined with monthly removal of unattached, infected nail by a healthcare professional with competence in nail procedures 4

Special Populations

• Diabetic patients: Strongly prefer terbinafine over itraconazole due to low risk of drug interactions and hypoglycemia 1
• Immunosuppressed patients: Prefer terbinafine or fluconazole over itraconazole due to reduced drug interactions with antiretrovirals and immunosuppressants 1
• Pediatric patients: Pulse itraconazole or daily terbinafine may be used, with cure rates of 88-100% 1

Important Clinical Considerations

• Clinical improvement does not equal mycological cure, with cure rates often 30% lower than apparent clinical improvement with topical antifungals 3
• The nail plate acts as a significant barrier, with drug concentration dropping 1000-fold from outer to inner nail surface 3
• Treatment failure rates of 20-30% are common even with the most effective agents 1
• Onychomycosis has high recurrence rates (40-70%), requiring preventive strategies 1

Common Pitfalls to Avoid

• Underdosing or insufficient treatment duration leads to poor outcomes 1
• Using topical therapy for extensive disease results in predictable failure 1
• Not considering drug interactions in patients on multiple medications, particularly with itraconazole 1
• Starting treatment without mycological confirmation is the most common cause of treatment failure 1

Adverse Effects

Terbinafine: Gastrointestinal symptoms, infections, and headache, but no significant difference in risk compared to placebo (RR 1.13) 5

Topical agents: Rare adverse effects, mainly local burning, pruritus, erythema, and periungual inflammation 3