What is the recommended dosage and treatment duration of terbinafine (antifungal medication) for athlete's foot?

Terbinafine for Athlete's Foot

For athlete's foot (tinea pedis), oral terbinafine 250 mg once daily for 1-2 weeks is the recommended systemic treatment, while topical terbinafine 1% cream applied once daily for 1 week is highly effective for localized disease. 1

Oral Terbinafine Dosing

• Adults and adolescents: 250 mg once daily for 1-2 weeks achieves mycological cure rates of 80-90%, which is significantly superior to longer courses of other antifungals 1, 2
• The 1-week regimen has similar efficacy to 4 weeks of clotrimazole 1% cream twice daily, but with faster clinical resolution 1
• When compared to itraconazole 100 mg daily over 2 weeks, terbinafine shows similar mycological efficacy but may have slightly lower relapse rates 1

Topical Terbinafine Dosing

• Terbinafine 1% cream applied once daily for 1 week is the preferred topical regimen for uncomplicated tinea pedis interdigitalis 3, 4
• This 1-week regimen achieves mycological cure rates of 93.5% at 4 weeks post-treatment, significantly superior to clotrimazole 1% cream used twice daily for 4 weeks (73.1% cure rate) 4
• Effective treatment rates (mycological cure plus minimal symptoms) reach 89.7% with 1 week of terbinafine versus 73.1% with 4 weeks of clotrimazole 4
• A film-forming solution formulation allows for single-dose treatment, which may improve compliance 3

When to Choose Oral vs. Topical Treatment

• Topical therapy is first-line for localized, uncomplicated tinea pedis interdigitalis 3
• Oral therapy is indicated for:
  • Chronic "moccasin-type" tinea pedis (hyperkeratotic plantar involvement) 5, 6
  • Extensive disease involving multiple areas of the foot 1
  • Failed topical therapy 1

Combination Therapy Considerations

• If a patient is already on oral terbinafine, adding ciclopirox olamine 0.77% cream or gel twice daily for 4 weeks provides complementary coverage through a different mechanism of action 7
• Ciclopirox achieves approximately 60% clinical and mycological cure at end of treatment and 85% two weeks after completion 1, 7

Critical Safety Monitoring

Before initiating oral terbinafine, obtain baseline liver function tests (ALT and AST) and complete blood count, particularly in patients with history of heavy alcohol consumption, hepatitis, or haematological abnormalities 1, 8

Key Warnings:

• Liver failure (potentially requiring transplant or fatal) has occurred with oral terbinafine; discontinue immediately if liver injury develops 8
• Taste disturbance can be severe, prolonged, or permanent; discontinue if this occurs 1, 8
• Smell disturbance may be prolonged or permanent 8
• Severe neutropenia: discontinue if neutrophil count ≤1,000 cells/mm³ 8
• Contraindicated in patients with active or chronic liver disease 1

Common Pitfalls to Avoid

• Do not use oral terbinafine for onychomycosis dosing (12 weeks) when treating tinea pedis – this is excessive and increases adverse event risk 8
• Warn patients about permanent taste/smell loss before starting treatment, as this can significantly impact quality of life 1, 8
• Consider underlying risk factors such as obesity and diabetes, which increase susceptibility and may affect treatment response 1
• Terbinafine is superior for Trichophyton species (the predominant cause of tinea pedis) but less effective against Microsporum species 1, 2

Preventive Measures to Recommend

• Thorough drying between toes after showers 1
• Daily sock changes 1
• Periodic cleaning of athletic footwear 1
• Foot powder use after bathing has been associated with decline in tinea pedis rates from 8.5% to 2.1% 1

Drug Interactions

• Terbinafine inhibits CYP2D6 and affects metabolism of desipramine, cimetidine, fluconazole, cyclosporine, rifampin, and caffeine 8
• Minimal drug-drug interactions compared to azole antifungals 1

Efficacy Timeline

Mycological cure rates continue to improve after treatment cessation due to terbinafine's fungicidal mechanism and residual tissue effect 9, 4. At 6 months post-treatment with oral terbinafine, 100% of patients with chronic foot infections remained in remission versus only 14% with griseofulvin 5.