Treatment Selection for Tinea Capitis in Children: Terbinafine vs. Itraconazole
The choice between terbinafine and itraconazole for pediatric tinea capitis depends entirely on the causative organism: terbinafine is superior for Trichophyton species infections, while itraconazole is reserved as second-line therapy when first-line agents fail, regardless of the organism. 1
Species-Directed Treatment Algorithm
For Trichophyton Species (T. tonsurans, T. violaceum, T. soudanense)
Terbinafine is the preferred choice when treating Trichophyton infections 1:
Dosing by weight:
- <20 kg: 62.5 mg daily for 2-4 weeks
- 20-40 kg: 125 mg daily for 2-4 weeks
40 kg: 250 mg daily for 2-4 weeks
Key advantage: Shorter treatment duration (2-4 weeks vs. 6-8 weeks for griseofulvin), which significantly improves compliance 1
Efficacy: Terbinafine shows much higher efficacy against Trichophyton species compared to Microsporum 1
For Microsporum Species (M. canis, M. audouinii)
Neither terbinafine nor itraconazole should be first-line for Microsporum infections. Griseofulvin remains superior for these organisms 1.
Critical pharmacologic limitation: Terbinafine is not excreted in sweat or sebum of prepubertal children and cannot be incorporated into the hair shaft in children, preventing it from reaching the scalp surface where Microsporum arthroconidia are located 1. This accounts for its relative inefficacy against Microsporum.
When to Use Itraconazole
Itraconazole is positioned as second-line therapy 1:
- Indication: Treatment failure with first-line agents (griseofulvin or terbinafine)
- Dosing: 50-100 mg daily for 4 weeks, or 5 mg/kg/day for 2-4 weeks
- Advantage: Has activity against both Trichophyton AND Microsporum species 1
- Strength of recommendation: C (weaker than first-line agents)
Second-Line Algorithm After Treatment Failure
If initial therapy fails:
- First assess compliance, drug absorption, and possible reinfection 1
- If clinical improvement but ongoing positive mycology: continue current therapy 2-4 more weeks
- If no clinical improvement:
- For Trichophyton infections initially treated with itraconazole → switch to terbinafine
- For Microsporum infections initially treated with itraconazole → switch to griseofulvin 1
Critical Caveats
Licensing Issues
- Itraconazole is NOT licensed in the UK for children ≤12 years with tinea capitis 1, though it is licensed in Europe for children >12 years
- This limits its use to off-label situations despite demonstrated safety and efficacy
Drug Interactions with Itraconazole
Itraconazole has significant drug interactions that must be considered 1:
- Enhanced toxicity with: warfarin, certain antihistamines (terfenadine, astemizole), antipsychotics (sertindole), midazolam, digoxin, cisapride, cyclosporine, simvastatin
- Decreased efficacy with: H2 blockers, phenytoin, rifampin
Terbinafine Safety Profile
While generally well-tolerated, terbinafine carries risks 2:
- Liver toxicity (requires baseline liver function tests)
- Taste/smell disturbances (may be permanent)
- Depressive symptoms
- Serious skin reactions
Practical Clinical Approach
When culture results are pending and you must start empirical therapy 1:
- Consider local epidemiology to predict the likely organism
- In North America: T. tonsurans predominates → terbinafine is reasonable first-line
- In Europe/areas with M. canis: griseofulvin is safer first-line choice
- Always obtain fungal culture before starting treatment to guide therapy if initial treatment fails 1
Direct Answer to Your Question: Between terbinafine and itraconazole specifically, terbinafine is better for Trichophyton infections (shorter course, first-line evidence), while itraconazole should be reserved for second-line use when first-line agents fail, particularly because it maintains activity against both organism types 1. However, neither should be first-line for Microsporum infections—griseofulvin remains superior for those cases 1.