What is the recommended treatment for onychomycosis (fingernail fungus)?

Treatment of Fingernail Onychomycosis

Oral terbinafine 250 mg daily for 6 weeks is the first-line treatment for fingernail fungus, offering the highest cure rates (80-90%) with fungicidal activity and superior efficacy compared to all other options. 1, 2, 3

Systemic Therapy: The Preferred Approach

Systemic therapy is almost always more successful than topical treatment and should be the default choice for fingernail onychomycosis. 1

First-Line: Terbinafine

• Dosing: 250 mg once daily for 6 weeks for fingernails 1, 3
• Mechanism: Fungicidal through inhibition of squalene epoxidase, directly killing dermatophytes 2
• Efficacy: Achieves 80-90% cure rates for fingernail infections, with the highest quality of evidence (A-I rating) 1
• Advantages: Shorter treatment duration, fungicidal rather than fungistatic, better compliance 1
• Monitoring: Obtain baseline liver function tests and complete blood count before starting 1, 3
• Key adverse effects: Reversible taste disturbance in 1:400 patients, idiosyncratic liver reactions, can aggravate psoriasis 1, 3
• Drug interactions: Plasma concentrations reduced by rifampicin, increased by cimetidine 1

Second-Line: Itraconazole

• Dosing: 200 mg twice daily for 1 week per month (pulse therapy), with 2 pulses recommended for fingernails 1, 2
• When to use: Active against Candida albicans, making it preferred when yeast infection is confirmed 1, 2
• Efficacy: Less effective than terbinafine for dermatophyte infections but achieves 92% cure rate for Candida onychomycosis 2
• Absorption: Take with food and acidic pH for optimal absorption 1, 2
• Monitoring: Liver function tests required for treatment durations longer than 1 month 1
• Major drug interactions: Enhanced toxicity with warfarin, terfenadine, astemizole, sertindole, midazolam, digoxin, cisapride, ciclosporin, and simvastatin 1

Third-Line: Fluconazole

• Dosing: 150-450 mg per week for 3 months for fingernail infections 1
• When to use: Alternative when terbinafine or itraconazole are contraindicated or not tolerated 1, 2
• Monitoring: Baseline liver function tests and complete blood count; monitor liver function in high-dose or prolonged therapy 1

Avoid: Griseofulvin

• Poor choice: Lengthy treatment (6-9 months for fingernails), poor cure rates (30-40%), high relapse rates 1, 2
• Only use when: Other agents are unavailable or contraindicated 2

Topical Therapy: Limited Role

Topical treatment should only be used for superficial white onychomycosis, very early distal lateral subungual onychomycosis, or when systemic therapy is contraindicated. 1, 2

Available Topical Options

• Amorolfine 5% lacquer: Applied once or twice weekly for 6-12 months, effective in approximately 50% of cases when infection is limited to distal portion 1, 2
• Ciclopirox 8% lacquer: Applied once daily for up to 48 weeks, useful for mild to moderate disease without lunula involvement 1, 4
• Efinaconazole 10% solution: FDA-approved topical option, though primarily studied for toenails 5, 6
• Tioconazole 28% solution: Applied twice daily for 6-12 months, variable cure rates (20-70%) 1

Critical Limitation

Topical therapies have significantly lower efficacy than oral agents and require much longer treatment duration with strict compliance 1, 2, 7

Essential Pre-Treatment Steps

Always confirm diagnosis with mycological examination (KOH preparation, fungal culture, or nail biopsy) before initiating treatment. 1, 5, 3, 8

• Treatment failure is common when diagnosis is made on clinical grounds alone 5
• Mycological confirmation identifies the causative organism, guiding appropriate therapy selection 1, 2
• Clinical appearance alone cannot distinguish fungal from non-fungal nail dystrophy 1

Special Populations

Diabetic Patients

• Preferred agent: Terbinafine due to lower risk of drug interactions and hypoglycemia 1, 2
• Avoid: Itraconazole is contraindicated in congestive heart failure, which has higher prevalence in diabetics 1
• Importance: Onychomycosis is a significant predictor for foot ulcers in diabetes 1, 2

Immunosuppressed Patients

• Preferred agents: Terbinafine or fluconazole due to lower risk of interactions with antiretrovirals 1
• Avoid: Itraconazole and ketoconazole have increased risk of interactions with antiretrovirals 1

Pediatric Patients

• First-line: Pulse itraconazole 5 mg/kg/day for 1 week per month, 2 pulses for fingernails 1, 2
• Alternative: Terbinafine weight-based dosing (62.5 mg/day if <20 kg, 125 mg/day for 20-40 kg, 250 mg/day if >40 kg) for 6 weeks 1, 2
• Higher cure rates: Pediatric patients achieve 88-100% cure rates, better than adults 1, 2

Candida Infections

• Preferred agent: Itraconazole 400 mg daily for 1 week per month, 2 pulses for fingernails 1, 2
• Efficacy: 92% cure rate with itraconazole versus 40% with pulse terbinafine 2
• Alternative: Fluconazole 50 mg daily or 300 mg weekly 2

Combination Therapy

Consider combining topical and systemic antifungals when response to monotherapy is likely to be poor. 1

• Provides antimicrobial synergy and wider antifungal spectrum 1
• Increases cure rates and suppresses resistant mutants 1
• Enhances tolerability and safety 1

Common Pitfalls to Avoid

• Don't start treatment without mycological confirmation: This is the most common cause of treatment failure 1, 5
• Don't use terbinafine for Candida infections: It has poor activity against yeasts; use itraconazole or fluconazole instead 2, 9
• Don't ignore drug interactions: Particularly with itraconazole, which interacts with numerous medications 1
• Don't expect immediate results: Complete cure takes months after treatment cessation due to slow nail growth 5, 3
• Don't assume treatment failure means resistance: Poor compliance is more common than true resistance 9

Monitoring During Treatment

Terbinafine

• Baseline liver function tests and complete blood count required 1, 3
• Warn patients to report persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, or pale stools immediately 3
• Discontinue if liver function tests elevate 3
• Monitor for taste or smell disturbances, which may be permanent 3

Itraconazole

• Monitor liver function tests for treatment durations longer than 1 month 1
• Check for drug interactions with concomitant medications 1

Fluconazole

• Baseline liver function tests and complete blood count 1
• Monitor liver function in high-dose or prolonged therapy 1

Expected Outcomes

• Mycological cure rates: Typically 30% better than clinical cure rates 1, 5
• Fingernail cure rates with terbinafine: 80-90% 1
• Optimal clinical effect: Seen months after mycological cure due to time required for healthy nail outgrowth 3
• Recurrence rates: 40-70%, requiring preventive strategies 2

Prevention of Recurrence

• Wear protective footwear in public bathing facilities 2, 7
• Use absorbent and antifungal powders in shoes 2, 9
• Keep nails short 2
• Avoid sharing nail clippers 2
• Treat all infected family members simultaneously 9
• Consider discarding old footwear or treating shoes with antifungal spray 9
• Disinfect shoes and socks 7