Onychomycosis Treatment
First-Line Treatment Recommendation
Oral terbinafine 250 mg once daily is the first-line treatment for dermatophyte onychomycosis (the most common type), given for 6 weeks for fingernails and 12 weeks for toenails, achieving cure rates of 80-90% for fingernails and 70-80% for toenails. 1
Mandatory Pre-Treatment Confirmation
Never initiate treatment without mycological confirmation—this is the most common cause of treatment failure. 1, 2
- Obtain KOH preparation with microscopy AND fungal culture before starting any antifungal therapy 1, 3
- Clinical appearance alone is insufficient for diagnosis 1
- Check baseline liver function tests (ALT and AST) before starting terbinafine, especially in patients with alcohol use, hepatitis history, or liver disease 1
Treatment Algorithm by Causative Organism
Dermatophyte Onychomycosis (Majority of Cases)
First-line: Oral terbinafine 250 mg daily 1
- Fingernails: 6 weeks of continuous therapy 1
- Toenails: 12 weeks of continuous therapy 1
- Terbinafine is superior to itraconazole both in vitro and in vivo 1
Second-line: Itraconazole pulse therapy 1
- 400 mg daily for 1 week per month 1
- Fingernails: 2 pulses (2 months total) 1
- Toenails: 3 pulses (3 months total) 1
Avoid griseofulvin due to lower efficacy (30-40% mycological cure) and higher relapse rates 1
Candida Onychomycosis (When Nail Plate Invaded by Yeast)
Itraconazole is the most effective agent for Candida nail infections 1
Topical Therapy: Limited Role
Topical therapy is inferior to systemic treatment except in very limited cases. 1, 2
When Topical Monotherapy Is Appropriate:
- Superficial white onychomycosis (SWO) affecting <50% of nail 2
- Very distal disease without matrix involvement 2
- Mild to moderate infection in patients with high risk of drug interactions 2
FDA-Approved Topical Agents:
- Apply once daily for up to 48 weeks 1, 4
- Requires monthly removal of unattached infected nail by healthcare provider 4
- Only for mild to moderate onychomycosis without lunula involvement 4
Efinaconazole 10% solution 5, 6
- More effective than ciclopirox in clinical trials 5
Amorolfine 5% lacquer (available in Europe) 1
- Apply once or twice weekly for 6-12 months 1
Critical Limitations of Topical Therapy:
- Do not use when dermatophytoma (compact fungal mass) is present—it prevents drug penetration 2
- Do not use when nail thickness exceeds 2 mm 2
- Minimum treatment duration of 6-12 months required 2
Special Population Considerations
Diabetic Patients
Terbinafine is the agent of choice 1
- Low risk of drug interactions 1
- No hypoglycemia risk 1
- Critical: Onychomycosis is a significant predictor of foot ulcers and cellulitis in diabetics—treatment prevents serious complications 1
Immunocompromised Patients (HIV, Transplant Recipients)
Terbinafine is preferred over itraconazole 1
- Lower risk of drug interactions with antiretrovirals and immunosuppressive medications 1
- Prevalence of onychomycosis in HIV-positive patients is approximately 30% 1
- Avoid griseofulvin—it is the least effective oral antifungal in HIV-positive patients 1
Pediatric Patients (Age 1-12 Years)
Terbinafine daily dosing based on weight: 1
- <20 kg: 62.5 mg/day 1
- 20-40 kg: 125 mg/day 1
40 kg: 250 mg/day 1
- Duration: 6 weeks for fingernails, 12 weeks for toenails 1
- Cure rates are higher in children than adults due to faster nail growth 1
Management of Treatment Failure (20-30% of Cases)
Common Causes of Failure:
- Poor adherence to treatment 1
- Poor drug absorption 1
- Immunosuppression 1
- Dermatophyte resistance 1
- Dermatophytoma subungual (compact fungal mass preventing drug penetration) 1
Strategies for Therapeutic Failure:
If dermatophytoma is present: Consider partial nail removal to allow drug penetration 1
If initial agent failed: Switch to alternative oral agent 1
Follow-Up and Realistic Expectations
- Reevaluate patients 3-6 months after initiating treatment 1
- Do not expect complete clinical normalization even with mycological cure—nails may have pre-existing dystrophy from trauma or non-fungal disease 1, 2
- Recurrence rates are approximately 25% 6
Prevention of Recurrence
Essential preventive measures to reduce 25% relapse rate: 6
- Wear protective footwear in communal bathing facilities, gyms, and hotel rooms to avoid re-exposure to T. rubrum 1
- Apply absorbent antifungal powders 1
- Wear cotton socks 1
- Keep nails short 1
- Avoid sharing toenail clippers 1
- Discard old footwear 1
- Promptly treat tinea pedis infections 7
Critical Pitfalls to Avoid
- Never treat based on clinical appearance alone—incorrect diagnosis is the most common cause of treatment failure 1, 2
- Never combine ciclopirox 8% with systemic antifungals—no studies have determined safety/efficacy of this combination 4
- Do not use topical therapy alone for moderate to severe disease—systemic therapy has significantly higher cure rates 1, 5
- Do not forget baseline liver function tests before starting terbinafine 1