What is the recommended treatment for extensive tinea corporis?

Treatment of Extensive Tinea Corporis

For extensive tinea corporis, oral antifungal therapy is the recommended treatment, with terbinafine 250 mg daily for 1-2 weeks as the preferred first-line agent, particularly for Trichophyton species infections. 1, 2

When to Use Oral vs. Topical Therapy

• Oral antifungals are indicated for extensive infections, treatment failures of topical therapy, or immunocompromised patients, while topical therapy is reserved for localized disease 1, 2
• The American College of Physicians specifically recommends oral antifungals for extensive infections rather than attempting topical therapy 2

First-Line Oral Treatment Options

Terbinafine (Preferred)

• Terbinafine 250 mg daily for 1-2 weeks achieves mycological cure rates >80% and is particularly effective against Trichophyton rubrum and T. mentagrophytes 2, 3
• Superior efficacy compared to griseofulvin, with 87.1% vs. 54.8% mycological cure rates at 6-week follow-up 3
• Shorter treatment duration (1-2 weeks) compared to other agents 2, 4
• Well tolerated with gastrointestinal disturbances (49%) being the most common side effect; serious adverse events are rare (0.04% incidence) 2
• One-week therapy with terbinafine 250 mg daily has demonstrated 100% mycological cure at 6-week follow-up in clinical trials 5

Itraconazole (Alternative)

• Itraconazole 100 mg daily for 15 days achieves 87% mycological cure rate, superior to griseofulvin's 57% 1, 2
• Alternative dosing: 200 mg daily for 7 days is also effective 4
• Licensed for children over 12 years in the UK, though used off-label in younger children in some countries 1
• Important drug interactions to consider: enhanced toxicity with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin 1

Treatment Selection Algorithm

Choose terbinafine as first-line unless contraindicated:

• Terbinafine is superior for Trichophyton tonsurans, T. rubrum, and T. mentagrophytes infections 1, 2, 3
• Switch to itraconazole if drug interactions preclude terbinafine use or if patient has contraindications (active/chronic liver disease, lupus erythematosus) 2
• Terbinafine has minimal drug-drug interactions compared to azoles 2

Critical Diagnostic Considerations Before Treatment

• Confirm dermatophyte infection via potassium hydroxide (KOH) preparation or fungal culture before initiating therapy 2
• Collect specimens using scalpel scraping, hair pluck, brush, or swab as appropriate to the lesion 1, 6
• Identifying the causative organism guides treatment selection 1, 2

Treatment Monitoring and Endpoints

• Mycological cure, not just clinical response, is the definitive treatment endpoint 2, 6
• Follow-up with repeat mycology sampling is recommended until mycological clearance is documented 1, 2
• If clinical improvement occurs but mycology remains positive, continue current therapy for an additional 2-4 weeks 2, 6
• If no clinical improvement, switch to second-line therapy (e.g., from terbinafine to itraconazole or vice versa) 6

Prevention of Recurrence (Essential Component)

• Screen and treat all family members, as over 50% of household contacts may be affected with anthropophilic species like T. tonsurans 1, 2, 6
• Clean all fomites (combs, brushes, towels) with disinfectant or 2% sodium hypochlorite solution 1, 2, 6
• Avoid skin-to-skin contact with infected individuals and do not share towels or personal items 1, 2
• Cover lesions during treatment to prevent transmission 1

Common Pitfalls and Caveats

• Do not use griseofulvin as first-line treatment: it requires longer treatment duration (6-8 weeks), is less effective than terbinafine, and has lower cure rates 1, 6
• Higher doses of terbinafine (500 mg) do not provide additional benefit over standard 250 mg dosing and should not be routinely used 7
• Fluconazole is a third-line option with significant limitations, including not being licensed for tinea in children under 10 years in the UK and being less cost-effective than terbinafine 1
• Assess compliance, drug absorption, organism sensitivity, and potential reinfection in cases of treatment failure 6
• Terbinafine is contraindicated in patients with active or chronic liver disease and lupus erythematosus 2