Treatment of Tinea Capitis (Scalp Ringworm)
Oral antifungal therapy is mandatory for tinea capitis—topical treatment alone is insufficient—with the choice of agent determined by the causative organism: terbinafine for Trichophyton species and griseofulvin for Microsporum species. 1, 2
Diagnostic Confirmation Before Treatment
- Collect scalp samples via scalpel scraping, hair pluck, brush, or swab for microscopy and culture to identify the causative dermatophyte 1, 2
- Potassium hydroxide (KOH) preparation provides rapid preliminary diagnosis while awaiting culture results 2, 3
- Treatment may be initiated empirically when cardinal clinical signs are present (scaling, lymphadenopathy, alopecia, or kerion) while awaiting mycology confirmation 1
First-Line Treatment Algorithm
Step 1: Identify the Causative Organism
For Trichophyton species (T. tonsurans, T. violaceum, T. soudanense):
- Terbinafine is the preferred first-line agent 1, 2
- Dosing by weight:
- Terbinafine is fungicidal and requires shorter treatment duration, improving compliance 1
For Microsporum species (M. canis, M. audouinii):
- Griseofulvin is the preferred first-line agent 1, 2
- Dosing by weight:
- Griseofulvin is the only licensed treatment for tinea capitis in children in the UK and many countries 1, 2, 3
- Should be taken with fatty foods to enhance absorption 1
Step 2: Critical Species-Specific Considerations
- Terbinafine has poor efficacy against Microsporum species because it cannot be incorporated into hair shafts in prepubertal children and is not excreted in sweat or sebum, failing to reach scalp surface arthroconidia 1
- Terbinafine may require 12-18 weeks for Trichophyton infections if standard duration fails 1
- Griseofulvin is increasingly expensive and requires prolonged treatment, potentially affecting compliance 1
Second-Line Treatment
If first-line therapy fails or is not tolerated:
- Itraconazole 5 mg/kg/day for 2-4 weeks is effective against both Trichophyton and Microsporum species 1, 2
- Fluconazole is an alternative for refractory cases with favorable tolerability and liquid formulation availability 2, 4
- For treatment failure, first assess compliance, drug absorption, organism sensitivity, and potential reinfection 1, 2
- If clinical improvement occurs but mycology remains positive, continue current therapy for an additional 2-4 weeks 1, 2
- If no clinical improvement, switch agents: terbinafine to griseofulvin for Microsporum, or griseofulvin to itraconazole for Trichophyton 1
Adjunctive Measures
- Topical antifungal shampoos (selenium sulfide 1% or ketoconazole 2%) reduce spore transmission but cannot replace oral therapy 1, 2, 5
- Screen and treat family members and close contacts, especially for T. tonsurans infections which spread person-to-person 2
- Maintain hygiene measures to control sources of infection and reinfection 3
Treatment Endpoint and Monitoring
- Mycological cure, not just clinical improvement, is the treatment endpoint 2, 3
- Continue medication until the infecting organism is completely eradicated as confirmed by repeat mycology 3
- Clinical relapse will occur if medication is discontinued prematurely 3
- Monitor for side effects: gastrointestinal disturbances and rashes occur in <8% with terbinafine, with only 0.8% requiring discontinuation 1
- Liver enzyme monitoring is generally unnecessary for treatment courses ≤4 weeks 4
Common Pitfalls to Avoid
- Never use topical therapy alone—it will not eradicate the infection from hair shafts 1, 3
- Do not use terbinafine as first-line for Microsporum infections—it has significantly reduced efficacy 1
- Avoid underdosing griseofulvin—higher doses (15-20 mg/kg/day) are needed due to increasing treatment failures at lower doses 1, 4
- Do not stop treatment based on clinical appearance alone—continue until mycological clearance is documented 2, 3
Contraindications
Griseofulvin: