What is the first-line treatment, including dosing and duration, for a 13-year-old with severe tinea corporis (ringworm)?

First-Line Treatment for Severe Tinea Corporis in a 13-Year-Old

For a 13-year-old with severe tinea corporis, oral terbinafine 250 mg once daily for 1-2 weeks is the first-line treatment, particularly if Trichophyton tonsurans is suspected or confirmed. 1, 2

Treatment Selection and Dosing

Primary Recommendation: Oral Terbinafine

• Terbinafine 250 mg once daily for 1-2 weeks is the preferred first-line agent for severe tinea corporis in adolescents 1, 2
• This dosing is particularly effective against Trichophyton tonsurans, the most common causative organism in adolescent wrestlers and athletes (>80% of cases) 1
• Terbinafine is well-tolerated, effective, and inexpensive, making it the optimal choice 2
• The 250 mg dose is appropriate for adolescents; higher doses (500 mg) have not shown additional benefit and are not recommended 3

Alternative Option: Itraconazole

• Itraconazole 100 mg once daily for 15 days is an effective alternative if terbinafine is contraindicated or unavailable 1, 4
• This regimen achieves an 87% mycological cure rate, superior to griseofulvin (57% cure rate) 1, 4
• Itraconazole is licensed for children over 12 years in many jurisdictions 4
• Important caveat: Itraconazole has significant drug interactions with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin that must be considered 4

Treatment Duration and Monitoring

Duration Considerations

• Treatment for 1-2 weeks with terbinafine is typically sufficient for tinea corporis 1, 5
• If using itraconazole, extend treatment to 15 days 1, 4
• The endpoint should be mycological cure, not just clinical improvement 4

Follow-Up Protocol

• Repeat mycology sampling is recommended until mycological clearance is documented 4
• If clinical improvement occurs but mycology remains positive, continue current therapy for an additional 2-4 weeks 6

Organism-Specific Considerations

When Terbinafine is Superior

• Terbinafine is specifically superior for Trichophyton tonsurans infections, the predominant organism in adolescent tinea corporis gladiatorum 1, 4
• It also demonstrates excellent efficacy against T. rubrum and T. mentagrophytes 1, 5

When to Consider Itraconazole

• Itraconazole may be preferred if the causative organism is unknown or if Microsporum species are suspected 4
• Consider itraconazole if terbinafine fails or is contraindicated 4

Common Pitfalls to Avoid

Do Not Use These Approaches

• Avoid griseofulvin as first-line treatment - it requires longer treatment duration, is less effective than terbinafine, and has lower cure rates 4
• Do not use topical therapy alone for severe tinea corporis - oral antifungal therapy is indicated when infection is resistant to topical treatment or extensive 4, 2
• Avoid combination antifungal-corticosteroid preparations as part of antifungal stewardship to prevent resistance 2
• Do not increase terbinafine dose to 500 mg - this provides no additional benefit over 250 mg 3

Prevention of Recurrence

Essential Preventive Measures

• Screen and treat all family members, as over 50% may be affected with anthropophilic species like T. tonsurans 4
• Clean all fomites (hairbrushes, combs, towels) with disinfectant or 2% sodium hypochlorite solution 4
• Avoid skin-to-skin contact with infected individuals and do not share towels or personal items 4
• Cover lesions during the treatment period 1