What is the recommended treatment for a fungal infection on the dorsum of the foot?

Treatment of Fungal Infection on the Dorsum of the Foot

For a dermatophyte infection on the dorsum of the foot (tinea pedis), topical terbinafine 1% cream applied once daily for 1 week is the recommended first-line treatment, offering superior efficacy to other topical agents with shorter treatment duration. 1

First-Line Topical Treatment

• Terbinafine 1% cream applied once daily for 1 week is the optimal choice, achieving mycological cure rates of approximately 90% and overall efficacy rates around 80% 2, 3
• This regimen is significantly superior to clotrimazole 1% cream applied twice daily for 4 weeks, with mycological cure rates of 93.5% versus 73.1% (p=0.0001) 4
• The fungicidal action of terbinafine allows for this remarkably short treatment duration compared to the fungistatic azoles 5, 6

Alternative Topical Options

If terbinafine is unavailable or contraindicated:

• Ciclopirox olamine 0.77% cream or gel applied twice daily for 4 weeks achieves approximately 60% cure rates at end of treatment and 85% two weeks post-treatment 1
• Clotrimazole 1% cream applied twice daily for 4 weeks is an over-the-counter alternative, though less effective than terbinafine 1, 4
• Butenafine cream applied twice daily for 2 weeks is another over-the-counter option 1

When to Consider Oral Therapy

Oral antifungals should be reserved for:

• Extensive or severe infections not responding to topical therapy 1
• Concurrent nail involvement (tinea unguium) 1
• Immunocompromised patients with widespread disease 1

Oral Treatment Regimens

• Terbinafine 250 mg once daily for 1 week has similar mycological efficacy to 4 weeks of topical clotrimazole but with faster clinical resolution 1
• Itraconazole 100 mg once daily for 2 weeks is an alternative, though terbinafine may have slightly lower relapse rates 1
• Oral terbinafine offers the advantage of once-daily dosing and briefer treatment periods than topical agents 1

Critical Adjunctive Measures

These non-pharmacologic interventions are essential to prevent recurrence:

• Careful and thorough drying between toes after showers 1
• Daily sock changes and periodic cleaning of athletic footwear 1
• Foot powder application after bathing has reduced tinea pedis rates from 8.5% to 2.1% over 3.5 years 1
• Wearing protective footwear in public bathing facilities, gyms, and hotel rooms to avoid re-exposure 1
• Discard old, moldy footwear or treat shoes with naphthalene mothballs in sealed plastic bags for minimum 3 days 1

Important Clinical Caveats

• Confirm diagnosis before treatment: Obtain KOH preparation, fungal culture, or appropriate specimen to identify the dermatophyte 7
• Obesity and diabetes are risk factors for tinea pedis and may require more aggressive management 1
• Yeasts and bacteria may coexist with dermatophytes in some forms of tinea pedis; antifungal agents alone will not eradicate these co-infections 7
• Monitor for rare adverse events with oral terbinafine, including isolated neutropenia and liver failure (typically in patients with pre-existing liver disease) 1
• Treat all infected family members simultaneously to prevent re-infection, as tinea pedis is contagious 1

Treatment Failure Considerations

If initial topical therapy fails:

• Re-evaluate diagnosis to exclude non-dermatophyte causes (Candida, bacteria) 7
• Consider switching to oral terbinafine 250 mg daily for 1-2 weeks 1
• Assess compliance with both medication application and hygiene measures 1
• Evaluate for underlying risk factors (diabetes, immunosuppression, obesity) 1