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	200 mg PO once daily × 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	150–300 mg PO weekly × 6 months	150–300 mg PO weekly × 12 months	Alternative, slower cure rate, especially for Candida.
Topical: Ciclopirox 8% lacquer	Apply daily × 24 weeks	Apply daily × 48 weeks	Only if <50% nail plate 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 = most effective & shortest duration.
Toenails always need longer treatment (slower growth than fingernails).
Pulse itraconazole is a good alternative for patients worried about long-term systemic use.
Topicals only for mild, superficial, or single-nail involvement.
Always check LFTs before and during systemic therapy.

Onychomycosis is caused by fungal invasion of the nail unit (nail plate, bed, and matrix). Predisposing factors:

Risk factors:

Increasing age (reduced nail growth, poor immunity)
Diabetes mellitus and peripheral vascular disease
Immunosuppression (HIV, chemotherapy, long-term steroids)
Repeated nail trauma or chronic exposure to moisture (farmers, housekeepers, swimmers)
Tinea pedis (“athlete’s foot”) as a source of spread to nails

Nail discoloration (yellow, brown, or white patches)
Thickened, brittle, and crumbly nail plate
Onycholysis (separation of nail from bed)
Subungual debris
More common in toenails than fingernails (slower growth, moist environment in shoes)

Most cases are treated as OPD unless there is severe immunosuppression or secondary bacterial infection needing inpatient care.

Systemic Antifungals (preferred in extensive or toenail disease):

Terbinafine (250 mg) 1×1 PO daily for 6 weeks (fingernails) or 12 weeks (toenails)
- Fungicidal against dermatophytes; first-line (IDSA, AAD guidelines).
Itraconazole pulse therapy: 200 mg PO BID for 1 week/month × 2 months (fingernails) or × 3 months (toenails).
Fluconazole (150–300 mg) PO weekly for several months (alternative, especially for Candida).

Topical Antifungals (for mild disease <50% nail involvement, no matrix involvement):

Keep nails short, filed, and clean
Use footwear that reduces moisture and friction
Treat coexisting tinea pedis (topical antifungal creams, e.g., terbinafine 1% cream OD × 2–4 weeks)
Avoid nail trauma and excessive manicuring
Educate about long treatment duration and relapse risk (20–30%)

Baseline liver function tests (LFTs) before systemic antifungals; repeat if therapy >6 weeks
Watch for side effects: hepatotoxicity (terbinafine, itraconazole), GI upset, rash
Complications if untreated: chronic pain, nail deformity, secondary bacterial cellulitis (especially in diabetics)

Clinical and mycological cure assessed at 6–12 months (nails grow slowly)
Relapse is possible; reinforce preventive care (keep feet dry, antifungal powder, treat family members with tinea pedis)

📌 Exam Pearl:

Terbinafine = best for dermatophytes (toenails).
Itraconazole = useful for Candida and non-dermatophytes.
Topical agents = only in limited nail involvement or when systemic therapy is contraindicated.
❌ Steroids are not used in onychomycosis (they worsen fungal growth).