What is the best treatment for a patient with onychomycosis (toe fungus)?

Treatment of Toenail Onychomycosis (Toe Fungus)

Oral terbinafine 250 mg daily for 12 weeks is the best treatment for toenail onychomycosis, achieving 70-80% cure rates and substantially outperforming all topical agents. 1, 2

First-Line Systemic Therapy

Terbinafine is the gold standard treatment:

• Dose: 250 mg once daily for 12 weeks for toenails (6 weeks for fingernails) 2
• Achieves 70% mycological cure (negative KOH plus negative culture) 2
• Clinical cure plus mycological cure occurs in 38% of patients 2
• Superior efficacy compared to azoles with similar adverse event profile 3
• Persists in nails for 6 months after treatment completion due to long half-life 4
• Optimal clinical effect appears months after treatment cessation as healthy nail grows out 2

Before prescribing terbinafine:

• Confirm diagnosis with KOH preparation, fungal culture, or nail biopsy 2
• Obtain baseline liver function tests 2
• Screen for contraindications including history of allergic reaction to terbinafine 2
• Review medications for drug-drug interactions, particularly tricyclic antidepressants, SSRIs, atypical antipsychotics, beta blockers, and tamoxifen 5

Monitor during treatment:

• Warn patients to report persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, or pale stools immediately 2
• Discontinue immediately if liver function tests elevate or symptoms of hepatotoxicity develop 2
• Alert patients about potential taste disturbance (can be severe and permanent) and smell disturbance 2
• Monitor for depressive symptoms 2

Alternative Systemic Therapy

If terbinafine is contraindicated or not tolerated:

Itraconazole Options

• Continuous dosing: 200 mg daily for 12 weeks 4
• Pulse dosing: 400 mg daily (200 mg twice daily) for 1 week per month for 3 pulses (3 months total) 4
• Must be taken with food and acidic beverages for optimal absorption 4
• Contraindicated in heart failure (negative inotropic effects) and active liver disease 4
• Requires baseline liver function tests and monitoring, especially with concomitant hepatotoxic drugs including statins 4
• Caution with statins due to increased statin levels 4

Fluconazole

• Dose: 150-450 mg once weekly for at least 6 months for toenails 4
• Fewer drug interactions with statins than itraconazole 4
• Obtain baseline liver function tests and CBC before initiating 4

Topical Therapy (Limited Role)

Topical treatment is inferior to systemic therapy in nearly all cases and should only be considered for: 1

• Very distal infection or superficial white onychomycosis 1
• Nail thickness ≤2 mm 1
• Absence of dermatophytoma, severe onycholysis, or slow nail outgrowth 1

If topical therapy is appropriate:

• Efinaconazole 10% solution: Apply once daily for 48 weeks; achieves ~50% mycological cure but only 15% complete cure 1
• Amorolfine 5% lacquer: Apply once or twice weekly for 6-12 months after filing down diseased nail; achieves ~50% clinical cure 1
• Ciclopirox 8% lacquer has poor efficacy (34% mycological cure, 8% clinical cure) 1
• Tioconazole 28% solution has very poor efficacy (22% cure rates) 1

Essential Adjunctive Measures

Combine with systemic therapy to enhance cure rates: 4

• Nail trimming and debridement improve treatment response 5
• Consider adding topical amorolfine or ciclopirox for antimicrobial synergy 4

Prevent 40-70% recurrence rate: 1, 4

• Decontaminate or discard old footwear 4
• Place naphthalene mothballs in shoes sealed in plastic bags for minimum 3 days 4
• Apply antifungal powders inside shoes regularly 1, 4
• Consider periodic spraying of terbinafine solution into shoes 4
• Wear protective footwear in public places 5
• Wear cotton absorbent socks 1, 4
• Keep nails short and clean 1, 4
• Treat all infected family members simultaneously 1

Monitoring and Follow-Up

• Monitor for at least 48 weeks from treatment start to identify potential relapse 4
• Assess both clinical improvement and mycological cure (negative microscopy and culture) 4
• Clinical relapse rate is approximately 15% for patients evaluated at least 6 months after achieving clinical cure 2
• Mean time to overall success is approximately 10 months for toenails 2

Critical Pitfalls to Avoid

• Never treat without confirming diagnosis - other nail conditions can mimic onychomycosis 2
• Do not use topical therapy alone for moderate-to-severe disease - cure rates are unacceptably low 1
• Do not prescribe terbinafine without baseline liver function tests - hepatotoxicity can lead to liver failure requiring transplant 2
• Do not ignore dermatophytoma - may require mechanical removal before antifungal therapy 4
• Do not forget footwear decontamination - fungal reservoirs cause reinfection 4