Antifungal Regimens for Onychomycosis: Drug Choices, Dosing, and Practical Pearls (Fungi, Fungus)

Antifungal Regimens for Onychomycosis

Drug	Fingernails	Toenails	Notes
Terbinafine	250 mg PO once daily × 6 weeks	250 mg PO once daily × 12 weeks	First-line for dermatophytes. Check baseline LFTs.
Itraconazole (continuous)	200 mg PO once daily × 6 weeks OR 100 mg PO BID × 6 weeks (off-label)	200 mg PO once daily × 12 weeks OR 100 mg PO BID × 12 weeks	Effective but higher drug–drug interactions.
Itraconazole (pulse)	200 mg PO BID × 1 week per month, repeat × 2 months	200 mg PO BID × 1 week per month, repeat × 3–4 months	Preferred when avoiding long continuous therapy.
Fluconazole (off-label)	150–300 mg PO weekly × 3 - 6 months	150–300 mg PO weekly × 6 - 12 months	Alternatively, a slower cure rate, especially for Candida.
Topical: Ciclopirox 8% lacquer	Apply daily × 24 weeks	Apply daily × 48 weeks	Only if <50% nail plate is involved, no matrix disease.
Topical: Efinaconazole 10% solution	Apply daily × 24 weeks	Apply daily × 48 weeks	Better efficacy than ciclopirox but costly.

✅ Key Takeaways for Exams & Practice

• Terbinafine PO = first-line (most effective, shortest duration) ✅

• Toenails require longer treatment (12 weeks) due to slow nail growth

• Itraconazole pulse therapy = alternative option (useful in compliance issues or contraindication to terbinafine)

• Topical therapy = only for mild disease (<50% nail, no matrix involvement)

• Always check LFT before systemic antifungals and monitor if prolonged use

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🦠 Why Onychomycosis Occurs

Onychomycosis = fungal infection of the nail plate + nail bed + matrix

Common organisms

• Dermatophytes (MOST COMMON) → Trichophyton rubrum

• Non-dermatophyte molds → Scopulariopsis

• Candida → more common in fingernails
  

Risk factors

• Elderly (↓ nail growth, ↓ immunity)

• Diabetes mellitus / peripheral vascular disease

• Immunosuppression (HIV, chemo, steroids)

• Chronic moisture (farmers, swimmers, housekeepers)

• Repeated trauma

• Tinea pedis (important source!)

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🔍 Clinical Features

• Nail discoloration (yellow / brown / white)

• Thickened, brittle nail

• Onycholysis

• Subungual debris

• Toenails > fingernails (moist + slow growth)

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🏥 Management of Onychomycosis

✅ Setting: OPD

• Most cases treated outpatient

• Admit only if severe immunocompromise or complication
  

1. Definitive Treatment

🔥 First-line (EXAM MUST REMEMBER)

👉 Terbinafine (250 mg) 1×1 po pc

• Fingernail: 6 weeks

• Toenail: 12 weeks ✔️ Fungicidal against dermatophytes ✔️ Recommended by AAD / IDSA
  

🟣 Alternative: Itraconazole

Continuous therapy

👉 Itraconazole (100 mg) 1×2 po pc for 12 weeks (toenail) OR 👉 Itraconazole (200 mg) 1×1 po pc for 12 weeks

⭐ Pulse therapy (HIGH-YIELD)

👉 Itraconazole (100 mg) 2×2 po pc for 1 week/month

• Fingernail: 2 cycles

• Toenail: 3–4 cycles
  

🟡 Alternative (less preferred)

👉 Fluconazole (150–300 mg) 1×1 weekly po for several months

• Useful in Candida
  

🧴 Topical (ONLY mild cases)

• Ciclopirox 8% daily × 48 weeks

• Efinaconazole 10% daily × 48 weeks

• Amorolfine 5% lacquer

❌ NOT for severe or matrix involvement

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2. Supportive Treatment

• Keep nails short, clean, and dry

• Avoid tight shoes / moisture

• Treat tinea pedis👉 Terbinafine cream (1%) 1×1 topical for 2–4 weeks

• Avoid trauma

• Educate: long treatment + recurrence risk

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3. Monitoring & Complications

• ✅ Baseline LFT before systemic therapy

• Repeat if >6 weeks or symptomatic

Side effects:

• Hepatotoxicity (important!)

• GI upset

• Rash

Complications:

• Nail deformity

• Secondary bacterial infection (esp. diabetic)

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4. Follow-up

• Clinical cure assessed at 6–12 months

• Reinforce prevention:

  • Keep feet dry

  • Antifungal powder

  • Treat contacts

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📌 Exam Pearls (VERY HIGH-YIELD)

• ✅ Terbinafine = drug of choice for dermatophyte toenail infection

• ✅ Itraconazole = broader spectrum (Candida, non-dermatophytes)

• ❌ Steroids are NOT used → worsen fungal infection

• ❗ Toenail = always longer treatment (12 weeks or pulse cycles)