What's the next step for my 4-year-old child with tinea capitis, who has shown no improvement after 5-6 weeks of treatment with griseofulvin (oral antifungal medication) and ketoconazole (generic name) shampoo?

Next Steps for Treatment-Resistant Tinea Capitis

You need to determine the causative organism immediately—if it's Microsporum species, griseofulvin is correct but may need dose adjustment or extended duration; if it's Trichophyton species, you should switch to terbinafine as it's significantly more effective. 1, 2

Critical First Step: Identify the Organism

• Contact your provider to confirm which fungal species was identified from the original culture (Microsporum vs. Trichophyton) 1, 2
• The choice of antifungal and next steps depend entirely on this result, as these organisms respond differently to treatment 1, 3

If Microsporum Species (e.g., M. canis):

• Continue griseofulvin but verify the dose is adequate: you need 15-20 mg/kg/day, and higher doses (20-25 mg/kg/day) may be required for resistant cases 1
• Griseofulvin must be given with fatty food (like whole milk, peanut butter, or ice cream) to increase absorption—this is critical and often overlooked 1, 4
• Extend treatment duration to 12-18 weeks if no improvement is seen, as Microsporum infections often require longer courses 1
• Terbinafine is ineffective for Microsporum in prepubertal children because it cannot be incorporated into hair shafts and doesn't reach the scalp surface where the fungus lives 1, 3

If Trichophyton Species (e.g., T. tonsurans, T. violaceum):

• Switch to terbinafine immediately as it achieves significantly higher cure rates than griseofulvin for Trichophyton infections 1, 5
• Dosing for a 4-year-old (likely under 20 kg): 62.5 mg daily for 2-4 weeks 1, 2
• If your child weighs 20-40 kg: 125 mg daily for 2-4 weeks 1
• Griseofulvin has lower efficacy (67.9% response) for Trichophyton compared to Microsporum (88.5% response) 2

Consider Treatment Failure Factors

• Poor compliance: Ensure medication is given daily without missed doses 1, 2
• Suboptimal absorption: Griseofulvin MUST be taken with fatty food—this increases absorption 4-10 fold in children 4
• Inadequate dosing: Many treatment failures occur with underdosing of griseofulvin 3
• Reinfection: Screen all family members and close contacts for infection, especially with T. tonsurans 2, 3

Second-Line Option if First-Line Fails

• Itraconazole 5 mg/kg/day for 2-4 weeks is effective against both Trichophyton and Microsporum species and serves as the recommended second-line agent 1, 3
• This should be considered if there is no clinical improvement after adjusting the current regimen 1

Important Monitoring Points

• The endpoint is mycological cure, not just clinical improvement—repeat culture is needed to confirm clearance 2, 3
• If clinical improvement occurs but culture remains positive, continue current therapy for an additional 2-4 weeks 1, 2
• If no clinical improvement at all after 5-6 weeks, this indicates treatment failure and requires switching agents 1

Adjunctive Measures to Continue

• Keep using ketoconazole shampoo once weekly as adjunctive therapy 2, 3
• Clean all hairbrushes and combs with bleach or 2% sodium hypochlorite solution 3
• Your child can attend school/daycare while on appropriate treatment 2, 3