What are the treatment options for fungal toenail infections?

Treatment of Fungal Toenail Infections

Oral terbinafine 250 mg once daily for 12 weeks is the first-line treatment for fungal toenail infections, with 70% mycological cure rates and superior efficacy compared to all other antifungal agents. 1, 2, 3

Confirm Diagnosis Before Treatment

• Obtain mycological confirmation through KOH preparation, fungal culture, or nail biopsy before starting any antifungal therapy 4
• The most common cause of treatment failure is incorrect diagnosis made on clinical grounds alone without laboratory confirmation 1
• Identifying the causative organism determines optimal treatment selection 4

Treatment Selection Algorithm

For Most Toenail Infections (Standard Approach)

First-line: Terbinafine

• Terbinafine 250 mg once daily for 12 weeks for toenail infections 1, 3
• Achieves 70% mycological cure and 38% complete clinical cure (0% nail involvement) 3
• Superior to all other oral antifungals for dermatophyte infections with the highest level of evidence (strength A, level 1+) 1
• Works by inhibiting squalene epoxidase, directly fungicidal against dermatophytes 2

Second-line: Itraconazole

• Itraconazole 400 mg daily for 1 week per month (pulse therapy), repeated for 3-4 pulses for toenails 4
• Particularly effective for Candida infections 1
• Achieves approximately 54% mycological cure in dermatophyte infections 2

For Limited Disease Only (Topical Therapy)

Topical therapy should only be used when ALL of the following criteria are met 1:

• Superficial white onychomycosis (SWO), OR
• Very early distal lateral subungual onychomycosis (DLSO) with <80% nail plate involvement and no lunula involvement, OR
• Oral therapy is contraindicated

Topical options:

• Amorolfine 5% nail lacquer: approximately 50% effectiveness in distal nail infections 1, 2
• Ciclopirox 8% nail lacquer: 34% mycological cure versus 10% with placebo 1
• Tioconazole 28% solution: variable results with 20-70% cure rates 1

For Candida Infections

• Itraconazole 400 mg daily for 1 week per month, repeated for 3-4 pulses 4
• Alternative: Fluconazole 150-450 mg weekly for at least 6 months 4

Special Populations

Diabetic Patients

• Strongly prefer terbinafine over itraconazole due to low risk of drug interactions and hypoglycemia 1, 2
• Onychomycosis is a significant predictor for foot ulcers in diabetics, making treatment particularly important 2

Immunosuppressed Patients

• Prefer terbinafine or fluconazole over itraconazole due to reduced drug interactions with antiretrovirals and immunosuppressants 1, 2

Pediatric Patients

• Pulse itraconazole 5 mg/kg/day for 1 week every month: 3 months for toenails 2
• Terbinafine based on weight: 62.5 mg/day if <20 kg, 125 mg/day for 20-40 kg, 250 mg/day if >40 kg 2
• Pediatric cure rates are higher than adults (88-100%) 1

Monitoring and Safety

For Terbinafine

• Baseline liver function tests and complete blood count recommended for patients with history of hepatotoxicity or hematological abnormalities 4
• Common adverse effects: headache, taste disturbance (may be prolonged or permanent), gastrointestinal upset 4, 3
• Instruct patients to immediately report persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, or pale stools 3

For Itraconazole

• Monitor hepatic function in patients with pre-existing liver issues or continuous therapy >1 month 4
• Common adverse effects: headache, gastrointestinal upset 4
• Higher risk of drug interactions with multiple medications compared to terbinafine 1

Setting Realistic Expectations

• Complete nail regrowth may take up to 18 months due to slow toenail growth 4
• The optimal clinical effect is seen months after mycological cure and cessation of treatment due to time required for outgrowth of healthy nail 3
• Treatment failure occurs in 20-30% of cases even with the most effective agents 1, 4
• Clinical relapse rate is approximately 15% at one year after completing therapy 3
• Onychomycosis has high recurrence rates (40-70%) without preventive measures 1, 2

Prevention of Recurrence

• Keep nails short 4
• Wear protective footwear in public bathing facilities 4, 2
• Apply antifungal powders to shoes and feet 4
• Wear cotton, absorbent socks 4
• Consider discarding heavily contaminated footwear or treating with antifungal solutions 4
• Treat all infected family members simultaneously 4
• Avoid sharing nail clippers 2

Critical Pitfalls to Avoid

• Do not use topical therapy for extensive disease (>80% nail involvement or lunula involvement) - this results in predictable failure 1
• Do not start treatment without mycological confirmation - incorrect diagnosis is the most common cause of treatment failure 1
• Do not underdose or use insufficient treatment duration - leads to poor outcomes 1
• Do not overlook drug interactions with itraconazole in patients on multiple medications 1
• Do not use griseofulvin as first-line - poor cure rates (30-40%), high relapse rates, and lengthy treatment duration (6-18 months) make it a third-line agent 2, 5

Enhanced Treatment for Severe Cases

• For partially detached nails with dense white lesions underneath (dermatophytomas), nail removal combined with oral therapy achieves cure rates close to 100% 4
• This combination approach is superior to oral therapy alone when dermatophytomas are present 4