What is the treatment for dermatophyte infections?

Treatment of Dermatophyte Infections

Oral terbinafine is the first-line treatment for dermatophyte infections, particularly for onychomycosis, with 250 mg daily for 6 weeks for fingernails and 12 weeks for toenails, due to its superior efficacy and lower relapse rates compared to other antifungals. 1, 2, 3

Treatment Options Based on Infection Site

Topical Treatment (for localized infections)

• First-line topical agents:
  • Allylamines (terbinafine, butenafine): Higher cure rates and shorter treatment courses than azoles 4
  • Azoles (clotrimazole, miconazole): Apply once or twice daily for 2-4 weeks for most infections 5
  • Apply for 4-6 weeks for tinea pedis 5

Oral Treatment (for extensive, severe, or resistant infections)

For Dermatophyte Onychomycosis:

1. Terbinafine (preferred):

   • Dosage: 250 mg once daily
   • Duration: 6 weeks for fingernails, 12-16 weeks for toenails
   • Mycological cure rate: 73-94% 2
   • Monitoring: Baseline liver function tests and complete blood count 1, 3

2. Itraconazole (alternative):

   • Dosage: 200 mg daily for 12 weeks continuously, OR
   • Pulse therapy: 400 mg daily for 1 week per month (2 pulses for fingernails, 3 for toenails)
   • Mycological cure rate: 45.8% at 48 weeks 2
   • Best taken with food and acidic pH 1

3. Fluconazole (when terbinafine/itraconazole not tolerated):

   • Dosage: 150-450 mg once weekly
   • Duration: 3 months for fingernails, at least 6 months for toenails 1

4. Griseofulvin (less preferred):

   • Dosage: 500-1000 mg daily
   • Duration: 6-9 months for fingernails, 12-18 months for toenails
   • Lower efficacy and higher relapse rates than newer agents 1, 6

For Tinea Capitis:

• Oral griseofulvin remains the standard treatment 4
• Terbinafine dosing for children is weight-based 2

For Extensive Tinea Pedis:

• Oral terbinafine 250 mg once daily for 1 week 2

Special Considerations

Treatment Selection Factors

• Infection type: Terbinafine generally preferred for dermatophytes; itraconazole may be more effective for Candida infections 2
• Comorbidities:
  • Diabetes: Terbinafine preferred due to fewer drug interactions 2
  • Liver disease: Terbinafine not recommended for chronic or active liver disease 3
  • Immunosuppression: Consider drug interactions; terbinafine or fluconazole preferred over itraconazole with antiretrovirals 2

Monitoring and Side Effects

• Terbinafine:

  • Monitor for hepatotoxicity, taste/smell disturbances, and depressive symptoms 3
  • Discontinue immediately if liver function tests elevate or symptoms of liver injury develop 3
  • Can aggravate psoriasis and cause lupus-like syndrome 1

• Itraconazole:

  • Contraindicated in heart failure 1
  • Monitor hepatic function in patients with pre-existing abnormalities or on continuous therapy >1 month 1

Prevention of Recurrence

• Keep nails short
• Avoid sharing nail clippers
• Wear protective footwear in public areas
• Apply antifungal powders in shoes and on feet
• Wear cotton, absorbent socks
• Consider discarding contaminated footwear or treating with naphthalene mothballs 1
• Treat all infected family members simultaneously 1

Treatment Failure Management

• Reasons for failure: poor compliance, poor absorption, immunosuppression, dermatophyte resistance, subungual dermatophytoma, zero nail growth 2
• Options for management:
  • Partial nail removal plus antifungal therapy
  • Alternative antifungal drug
  • Complete nail avulsion combined with antifungal therapy 2

Recurrence rates for onychomycosis are high (40-70%), emphasizing the importance of preventive measures and appropriate follow-up 2.