What is the treatment for onychomycosis?

Treatment of Onychomycosis

Terbinafine is the first-line treatment for dermatophyte onychomycosis due to its superior efficacy and should be administered at a dose of 250 mg daily for 6 weeks in fingernail infections and 12-16 weeks in toenail infections. 1

First-Line Systemic Treatments

Dermatophyte Onychomycosis (Most Common Type)

• Terbinafine is the preferred first-line treatment for dermatophyte onychomycosis with higher cure rates and lower relapse rates compared to other antifungals 1
• Dosing: 250 mg daily for 6 weeks in fingernail infections and 12-16 weeks in toenail infections 1
• Baseline liver function tests and complete blood count are recommended in patients with history of hepatotoxicity or hematological abnormalities 1
• Terbinafine demonstrates excellent fungicidal activity against dermatophytes with mycological cure rates of 70-80% for toenail infections and 80-90% for fingernail infections 1, 2
• Common adverse effects include headache, taste disturbance, and gastrointestinal upset; it can also aggravate psoriasis and cause a subacute lupus-like syndrome 1

Alternative First-Line Treatment

• Itraconazole is an effective alternative first-line treatment 1
• Dosing options:
  • Continuous: 200 mg daily for 12 weeks 1
  • Pulse therapy: 400 mg daily for 1 week per month (2 pulses for fingernails, 3 pulses for toenails) 1
• Itraconazole is optimally absorbed with food and an acidic pH 1
• Monitoring of hepatic function tests is recommended in patients with pre-existing abnormal results, those receiving continuous therapy for more than a month, or with concomitant use of hepatotoxic drugs 1
• Common adverse effects include headache and gastrointestinal upset 1

Second-Line Treatments

• Fluconazole may be useful for patients unable to tolerate terbinafine or itraconazole 1
• Dosing: 150-450 mg weekly for 3 months in fingernail infections and at least 6 months in toenail infections 1
• Griseofulvin has lower efficacy and higher relapse rates compared to newer antifungals and is not recommended as first-line therapy 1, 3

Treatment Based on Causative Organism

Candida Onychomycosis

• Itraconazole is the most effective agent for Candida onychomycosis 1
• Dosing: 400 mg daily for 1 week per month, repeated for 2 months in fingernail infection 1
• For toenail Candida infections (less common), 3-4 pulses are recommended 1
• Fluconazole is an effective alternative if itraconazole is contraindicated 1

Nondermatophyte Mold Infections

• Treatment is often difficult and may require longer courses 1
• Itraconazole has broader antimicrobial coverage for nondermatophyte molds compared to terbinafine 1
• Aspergillus species show excellent susceptibility to itraconazole 1

Topical Treatments

• Generally less effective than systemic therapy except in very distal infection or superficial white onychomycosis 1
• Options include:
  • Amorolfine: 5% lacquer applied once or twice weekly for 6-12 months 1
  • Ciclopirox: 8% lacquer applied once daily for up to 48 weeks 1, 4
  • Tioconazole: 28% solution applied twice daily for 6-12 months 1
• Topical treatments are more appropriate for mild-to-moderate infections or when systemic therapy is contraindicated 1

Special Populations

Children

• Onychomycosis is less common in children (prevalence <0.5%) 1
• First-line treatments:
  • Terbinafine: 62.5 mg/day if weight <20 kg, 125 mg/day for 20-40 kg, 250 mg/day if >40 kg; for 6 weeks in fingernails and 12 weeks in toenails 1
  • Itraconazole: Pulse therapy at 5 mg/kg/day for 1 week per month (2 pulses for fingernails, 3 pulses for toenails) 1

Diabetic Patients

• Up to one-third of diabetics may have onychomycosis, which is a significant predictor for foot ulcers 1
• Terbinafine is preferred over itraconazole due to lower risk of drug interactions and contraindications in cardiac disease 1

Immunosuppressed Patients

• Higher prevalence in immunosuppressed populations 1
• Terbinafine and fluconazole are preferred in HIV patients due to lower risk of interactions with antiretrovirals 1

Prevention of Recurrence

• Always wear protective footwear in public bathing facilities, gyms, and hotel rooms 1
• Apply antifungal powders to shoes and feet 1
• Keep nails short and avoid sharing nail clippers 1
• Consider disinfecting contaminated footwear or discarding heavily contaminated shoes 1

Common Pitfalls and Caveats

• Treatment should not be commenced before mycological confirmation of infection 1
• In cases of treatment failure, consider:
  • Poor compliance
  • Poor drug absorption
  • Misdiagnosis
  • Presence of dermatophytoma (fungal mass within the nail) 1
• Recurrence rates are high (40-70%), requiring preventive measures after successful treatment 1
• Monitoring liver function is essential with systemic antifungals, especially with pre-existing liver conditions or concomitant hepatotoxic medications 1