What is the recommended treatment for onychomycosis (fungal infection of the nail)?

Treatment of Onychomycosis

Terbinafine is the first-line treatment for onychomycosis, with oral terbinafine 250 mg daily recommended for 6 weeks in fingernail infections and 12-16 weeks in toenail infections. 1, 2, 3

Diagnostic Confirmation

• Mycological confirmation through microscopy and culture should be obtained before initiating antifungal treatment 1, 2
• FDA labeling specifically requires appropriate nail specimens (KOH preparation, fungal culture, or nail biopsy) to confirm diagnosis before starting treatment 3

Treatment Algorithm for Dermatophyte Onychomycosis

First-line Treatment:

• Oral terbinafine 250 mg daily for 6 weeks in fingernail infections and 12-16 weeks in toenail infections 1, 2
• Terbinafine is superior to other antifungals both in vitro and in vivo for dermatophyte onychomycosis 1
• A large randomized trial demonstrated complete cure in 55% of patients receiving terbinafine compared to 26% with itraconazole at 72-week follow-up 1
• Long-term studies show significantly lower relapse rates with terbinafine (23%) compared to itraconazole (53%) 1

Second-line Treatment:

• Itraconazole 200 mg daily for 12 weeks continuously, or as pulse therapy at 400 mg daily for 1 week per month (2 pulses for fingernails, 3 pulses for toenails) 1
• Fluconazole 450 mg once weekly (although not licensed for onychomycosis) 1, 2

Topical Treatment:

• Topical therapy alone is generally inferior to systemic therapy except in very distal infection 1
• Ciclopirox 8% nail lacquer can be used for mild to moderate onychomycosis in immunocompetent patients without lunula involvement 4
• Requires removal of unattached, infected nails monthly by a healthcare professional 4

Treatment for Candida Onychomycosis

• Itraconazole is the most effective agent for candidal onychomycosis where the nail plate is invaded 1, 2
• For candidal paronychia, topical treatment with antiseptics or imidazole lotion alternating with antibacterial lotion is usually effective 1

Special Populations

Diabetic Patients:

• Terbinafine is preferred due to lower risk of drug interactions and no negative inotropic effects 1, 2
• Itraconazole is contraindicated in congestive heart failure, which is more prevalent in diabetics 1
• Topical treatments may be appropriate for mild-to-moderate infections where drug interaction risk is high 1

Immunosuppressed Patients:

• Terbinafine or fluconazole are preferred due to fewer interactions with antiretrovirals 1, 2
• Griseofulvin is the least effective oral antifungal in immunosuppressed patients 1

Pediatric Patients:

• Terbinafine is recommended at weight-based dosing: 62.5 mg daily if <20 kg, 125 mg daily for 20-40 kg, and 250 mg daily if >40 kg 1
• Treatment duration remains 6 weeks for fingernails and 12 weeks for toenails 1

Monitoring and Safety

• Baseline liver function tests and complete blood count are recommended in patients with history of heavy alcohol consumption, hepatitis, or hematological abnormalities 1
• Terbinafine is not recommended in patients with active or chronic liver disease due to rare reports of serious hepatic toxicity 1
• Most common side effects of terbinafine are gastrointestinal (49%) and dermatological events (23%), with serious adverse events occurring in only 0.04% of patients 1

Treatment Pitfalls and Caveats

• Continuous terbinafine regimens show significantly higher efficacy (76.67%) compared to pulse regimens (26.67%) 5
• Treatment failure may occur due to poor compliance, inadequate drug penetration, or presence of dermatophytomas 1, 2
• Recurrence rates are high (40-70%), highlighting the need for patient education on prevention 2, 6
• Taste disturbance is a rare but potentially permanent adverse effect of terbinafine that patients should be warned about 1
• Concomitant use of topical ciclopirox and systemic antifungals is not recommended due to lack of studies on potential reduced effectiveness 4