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 at higher doses 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, 5
- 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 terbinafine 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
Monitoring and Treatment Endpoint
- Treatment endpoint is mycological cure, not merely clinical improvement 2
- Repeat mycology sampling until clearance is achieved to prevent relapse 2, 3
- Clinical relapse occurs if medication is discontinued before complete organism eradication 3
- Monitoring for liver enzyme elevations is generally unnecessary if therapy duration is ≤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—failure rates are high 1
- Avoid premature discontinuation based on clinical improvement alone without mycological confirmation of cure 2, 3
- Griseofulvin is contraindicated in lupus erythematosus, porphyria, and severe liver disease 1
- Rifampicin decreases griseofulvin plasma concentration; cimetidine increases it 1