What is the recommended systemic treatment regimen for tinea capitis in children, including first‑line agents, dosing, duration, and adjunctive measures?

Treatment of Tinea Capitis in Children

Organism-Directed First-Line Therapy

For Trichophyton species infections, use terbinafine as first-line therapy with weight-based dosing for 2-4 weeks; for Microsporum species infections, use griseofulvin 15-20 mg/kg/day for 6-8 weeks. 1, 2

Terbinafine Dosing for Trichophyton Species

• Children <20 kg: 62.5 mg daily for 2-4 weeks 1, 2
• Children 20-40 kg: 125 mg daily for 2-4 weeks 1, 2
• Children >40 kg: 250 mg daily for 2-4 weeks 1, 2

Terbinafine offers superior efficacy against Trichophyton tonsurans with a shorter treatment duration that improves compliance, and gastrointestinal disturbances or rashes occur in less than 8% of children. 1 The shorter 2-4 week course is a major advantage over griseofulvin's 6-8 week requirement. 1

Critical caveat: Terbinafine fails against Microsporum species because it cannot be incorporated into hair shafts in prepubertal children and doesn't reach the scalp surface where arthroconidia are located. 1 Never use terbinafine for Microsporum infections. 1

Griseofulvin Dosing for Microsporum Species

• Children <50 kg: 15-20 mg/kg/day for 6-8 weeks 1, 2, 3
• Children >50 kg and adults: 1 g/day for 6-8 weeks 1, 2, 3

Griseofulvin is the preferred agent for Microsporum species and remains the only licensed treatment for tinea capitis in many countries. 1 Eight weeks of griseofulvin is significantly more effective than 4 weeks of terbinafine for confirmed Microsporum infection. 1 Higher doses (20-25 mg/kg/day) are increasingly needed due to rising treatment failures with lower doses. 1, 4

When to Start Treatment Empirically

Start systemic antifungal therapy immediately before mycology results if any cardinal clinical signs are present: scale, lymphadenopathy, alopecia, or kerion. 1

Diagnostic Specimen Collection

• Collect scalp samples via scrapings, hair pluck, brush, or swab for microscopy and culture to confirm infection and identify the causative organism. 1
• Potassium hydroxide preparation provides rapid preliminary diagnosis while awaiting culture results. 1
• Oral therapy is mandatory for both clinical and mycological cure—topical therapy alone cannot eradicate scalp infections and should never be used as monotherapy. 1, 5

Second-Line Options for Treatment Failure

If initial therapy fails, consider poor compliance, suboptimal drug absorption, organism insensitivity, or reinfection. 1

Treatment Adjustment Algorithm

• If clinical improvement but positive mycology persists: Continue current therapy for an additional 2-4 weeks 1
• If no clinical improvement occurs: Switch to second-line therapy 1

Second-Line Agents

• Itraconazole: 5 mg/kg/day for 2-4 weeks (or 50-100 mg/day for 4 weeks), effective against both Trichophyton and Microsporum species 1, 2
• Fluconazole: Alternative for refractory cases with favorable tolerability profile and availability in liquid form 1, 2

Important drug interactions with itraconazole: Enhanced toxicity with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin; contraindicated in heart failure. 2

Adjunctive Measures

Topical Therapy

Use sporicidal shampoos (selenium sulfide or ketoconazole 2%) as adjunctive treatment only to reduce spore transmission and remove adherent scales. 1, 4 While one small study showed ketoconazole 2% shampoo alone reduced viable arthroconidia, 6 systemic therapy remains mandatory for cure. 1, 5

Contact Screening and Environmental Decontamination

• Screen and treat all family members and close contacts, especially for T. tonsurans infections where over 50% of family members may be affected. 1, 7
• Cleanse hairbrushes and combs with bleach or 2% sodium hypochlorite solution. 1
• Avoid sharing towels, combs, and other personal items. 7

School Attendance

Children receiving appropriate systemic and adjunctive topical therapy can attend school or nursery—exclusion is impractical and unnecessary. 1

Special Clinical Scenarios

Kerion Management

• Initiate oral systemic antifungal therapy immediately without awaiting culture results. 1
• Add topical or oral corticosteroids to alleviate severe inflammatory symptoms. 1
• Recognize that kerion is a fungal-driven inflammatory response, not a primary bacterial abscess, though secondary bacterial infection should be evaluated when clinically indicated. 1, 4

Dermatophytid (Id) Reaction

• Pruritic papular eruptions appearing after antifungal initiation represent a cell-mediated response to dying dermatophytes. 1
• Do not discontinue systemic antifungal therapy. 1
• Provide symptomatic relief with topical corticosteroids (or oral steroids in severe cases) while continuing the antifungal regimen. 1

Favus (Chronic Variant)

• Identify yellow, cup-shaped crusted lesions ("scutula") most often caused by Trichophyton schoenleinii. 1
• Recognize this can lead to scarring (cicatricial) alopecia if untreated. 1

Monitoring and Treatment Endpoint

The definitive endpoint is mycological cure (negative microscopy and culture), not just clinical improvement. 1, 2

• Repeat mycology sampling at the end of standard treatment period 1, 2
• Continue monthly sampling until mycological clearance is documented 1, 2
• Clinical relapse will occur if medication is not continued until the infecting organism is eradicated 3

Safety Monitoring

Baseline liver function tests are generally unnecessary if therapy is limited to ≤4 weeks, though monitoring is recommended for pre-existing hepatic abnormalities or prolonged therapy. 2, 4