What is the treatment for a patient with onychomycosis (fungal infection of the toenail)?

Treatment for Toenail Fungal Infection

Oral terbinafine 250 mg daily for 12-16 weeks is the first-line treatment for toenail onychomycosis caused by dermatophytes, achieving cure rates of 70-80%. 1

Confirm the Diagnosis First

Before starting any treatment, mycological confirmation is essential through KOH preparation, fungal culture, or nail biopsy. 2, 3 Treatment failure commonly occurs when diagnosis is made on clinical grounds alone without laboratory confirmation. 4

Treatment Selection Based on Causative Organism

For Dermatophyte Infections (Most Common)

Oral terbinafine is superior to all other options:

• Terbinafine 250 mg daily for 12-16 weeks is the treatment of choice with the highest cure rates (70-80% for toenails). 1, 2
• Terbinafine is the only oral fungicidal antimycotic and demonstrates superior efficacy compared to itraconazole both in vitro and in vivo. 1
• It is strongly lipophilic, distributes well into nails, and persists for 6 months after treatment completion. 1
• Common adverse effects include headache, taste disturbance, and gastrointestinal upset. 2
• Baseline liver function tests and complete blood count are recommended for patients with history of hepatotoxicity or hematological abnormalities. 2

Alternative oral option:

• Itraconazole 400 mg daily for 1 week per month (pulse therapy), repeated for 3-4 pulses is the next best alternative if terbinafine is contraindicated. 2
• Itraconazole is a potent CYP3A4 inhibitor with significant drug interaction potential, making it less suitable for patients on multiple medications. 5

For Candida Infections

• Itraconazole 400 mg daily for 1 week per month, repeated for 3-4 pulses is recommended. 2
• Fluconazole 150-450 mg weekly for at least 6 months is an alternative. 2

Topical Therapy (Limited Role)

Topical treatments are inferior to systemic therapy except in very distal infections or superficial white onychomycosis. 1 However, they may be considered for:

• Mild to moderate disease without lunula involvement in patients who cannot tolerate oral therapy. 6, 7
• Efinaconazole 10% solution daily for 48 weeks achieves mycological cure rates approaching 50%. 1
• Amorolfine 5% lacquer once or twice weekly for 6-12 months is another option. 1
• Ciclopirox 8% lacquer daily for up to 48 weeks achieves only 34% mycological cure versus 10% with placebo, with clinical cure of just 8%. 1, 6

Adjunctive Measures to Improve Success

Nail debridement is critical:

• Monthly removal of unattached, infected nail by a healthcare professional significantly improves treatment outcomes. 2, 6, 7
• For dense subungual dermatophytomas (tightly packed fungal masses visible as white lesions), partial nail removal is necessary before starting oral therapy to achieve cure rates approaching 100%. 1, 2

Managing Treatment Failure

The consistent 20-30% failure rate with terbinafine is most commonly due to: 1, 2

• Poor compliance 2
• Poor drug absorption 2
• Immunosuppression 2
• Presence of dermatophytoma requiring nail removal 1, 2
• Incorrect diagnosis (non-dermatophyte infection) 4

For treatment failures, either switch to an alternative oral agent or perform nail removal combined with a further course of therapy. 1

Prevention of Recurrence

Recurrence rates are approximately 25% without preventive measures. 7 Weekly topical antifungal prophylaxis following cure significantly reduces recurrence. 8

Additional preventive strategies include: 2

• Keeping nails short 2
• Wearing protective footwear in public bathing facilities 2
• Applying antifungal powders to shoes and feet 2
• Wearing cotton, absorbent socks 2
• Treating all infected family members simultaneously 2
• Discarding or treating heavily contaminated footwear 2

Important Caveats

• Complete nail regrowth takes up to 18 months due to slow toenail growth rates. 2
• Nail appearance may not return to completely normal if pre-existing dystrophy was present. 2
• Concomitant use of topical ciclopirox with systemic antifungals is not recommended as no studies have evaluated potential interference. 6
• Griseofulvin is no longer a treatment of choice due to lower efficacy (30-40% cure rates), longer treatment duration (12-18 months), and greater drug interaction risk. 1