What are the treatment options for fungal nail infections?

Treatment Options for Fungal Nail Infections

For dermatophyte nail infections (the most common type), terbinafine 250 mg daily is the first-line treatment: 6 weeks for fingernails and 12 weeks for toenails, offering superior cure rates and lower relapse rates compared to other antifungals. 1

Confirm the Diagnosis First

• Always obtain mycological confirmation before starting treatment through KOH preparation and fungal culture to identify whether the infection is caused by dermatophytes (most common), yeasts (Candida), or nondermatophyte molds 1, 2
• Treatment varies significantly based on the causative organism, making identification crucial 2

Treatment by Organism Type

Dermatophyte Infections (Most Common)

Terbinafine is the superior choice:

• Dosing: 250 mg once daily for 6 weeks (fingernails) or 12 weeks (toenails) 1, 3
• Efficacy: Achieves 70-80% mycological cure rates for toenails and 79% for fingernails 3, 4
• Mechanism: Truly fungicidal (not just fungistatic) with the lowest MIC against dermatophytes of all available agents 1
• Advantages: Higher cure rates, lower relapse rates (~15%), and better compliance than itraconazole for dermatophytes 1

Alternative: Itraconazole (less effective for dermatophytes)

• Continuous dosing: 200 mg daily for 12 weeks 1
• Pulse dosing: 400 mg daily for 1 week per month—2 pulses for fingernails, 3 pulses for toenails 1
• Note: Itraconazole has an MIC 10 times higher than terbinafine against dermatophytes and is less effective overall 1

Candida (Yeast) Infections

Itraconazole is first-line for Candida:

• Pulse therapy: 400 mg daily for 1 week per month—2 pulses for fingernails, 3-4 pulses for toenails 1
• Continuous therapy: 200 mg daily for minimum 4 weeks (fingernails) or 12 weeks (toenails) 1
• Rationale: Itraconazole is more active against yeasts than terbinafine and offers shorter treatment duration 1

Alternative: Fluconazole

• Dosing: 50 mg daily or 300 mg weekly for minimum 4 weeks (fingernails) or 12 weeks (toenails) 1
• Use when: Contraindications exist for itraconazole 1

Terbinafine for Candida (requires longer treatment):

• Effective only with extended courses: 16-48 weeks at 250 mg daily 1, 5
• Achieves 60-85% cure rates with prolonged therapy but impractical compared to azoles 1, 5

Nondermatophyte Molds

• Itraconazole has broader coverage for Scopulariopsis, Aspergillus, and other molds 1
• Terbinafine shows lowest activity against most nondermatophyte molds despite good dermatophyte activity 1
• Clinical efficacy often doesn't correlate with in vitro susceptibility testing 1

Safety Monitoring

For Terbinafine:

• Baseline liver function tests (ALT, AST) required before starting 3
• Monitor for hepatotoxicity symptoms: persistent nausea, fatigue, jaundice, dark urine, right upper abdominal pain 3
• Discontinue immediately if liver symptoms develop 3
• Common side effects: taste disturbance (1:400 patients, usually reversible), headache, GI upset 1, 3
• Rare but serious: permanent taste/smell loss, depressive symptoms, severe skin reactions 3

For Itraconazole:

• Monitor liver function if treatment exceeds 1 month or pre-existing liver disease 1
• Significant drug interactions: warfarin, terfenadine, astemizole, midazolam, digoxin, cisapride, cyclosporine, simvastatin 1
• Contraindicated in pregnancy 1

Important Clinical Caveats

Timing of Clinical Response:

• Optimal clinical effect occurs months after treatment completion due to slow nail growth 3
• Toenails require approximately 10 months total for complete regrowth; fingernails require 4 months 3
• Nail appearance may never return to completely normal if pre-existing dystrophy was present 2

Treatment Failure Occurs in 20-30% of Cases Due To:

• Poor compliance 2
• Poor drug absorption 2
• Immunosuppression 2
• Dermatophyte resistance 2
• Presence of dermatophytoma (dense fungal mass under nail requiring physical removal) 2

When to Consider Nail Removal:

• Partial nail avulsion combined with oral therapy achieves cure rates close to 100% 2
• Indicated for dermatophytomas (visible white masses under partially detached nails) 2
• Consider for severe infections (Grade 3) with spreading infection 6

Prevention of Recurrence

• Keep nails trimmed short 2
• Wear protective footwear in public bathing facilities 2
• Apply antifungal powders to shoes and feet 6, 2
• Wear cotton, absorbent socks 2
• Discard or treat heavily contaminated footwear with antifungal solutions 2
• Treat all infected family members simultaneously 2
• Address predisposing factors: hyperhidrosis, underlying conditions 6

Obsolete Treatments

Griseofulvin is no longer recommended:

• Poor cure rates and high relapse rates despite low cost 1
• Requires lengthy treatment (12+ months) 1
• Both direct and historical comparisons show inferiority to terbinafine and itraconazole 1