Treatment of Scalp Ringworm (Tinea Capitis)
Oral antifungal therapy is mandatory for scalp ringworm—topical treatments alone will not work—and your first-line choice depends entirely on which fungus is causing the infection: use terbinafine for Trichophyton species (2-4 weeks) and griseofulvin for Microsporum species (6-8 weeks). 1, 2
Diagnostic Approach Before Treatment
Collect scalp samples immediately via scraping, hair pluck, brush, or swab for microscopy and culture to identify the causative organism. 1, 3 However, start treatment empirically before mycology results return if any cardinal clinical signs are present: scaling, lymphadenopathy, alopecia, or kerion formation. 1
Potassium hydroxide microscopy provides rapid preliminary diagnosis while you wait for culture results to confirm the specific organism. 1
First-Line Treatment Algorithm
For Trichophyton Species (Most Common in North America)
Terbinafine is the preferred agent due to its fungicidal activity, superior efficacy, and shorter treatment duration that improves compliance. 1, 2
Weight-based dosing for terbinafine: 1, 3
- Under 20 kg: 62.5 mg/day for 2-4 weeks
- 20-40 kg: 125 mg/day for 2-4 weeks
- Over 40 kg: 250 mg/day for 2-4 weeks
Gastrointestinal disturbances and rashes occur in less than 8% of children. 1
For Microsporum Species
Griseofulvin is the preferred agent and significantly more effective than terbinafine for Microsporum infections (88.5% response rate). 1, 2 Terbinafine fails against Microsporum because it cannot be incorporated into hair shafts in prepubertal children and doesn't reach the scalp surface where arthroconidia are located. 1
Dosing for griseofulvin: 1, 3, 4
- Under 50 kg: 15-20 mg/kg/day for 6-8 weeks
- Over 50 kg and adults: 1 g/day for 6-8 weeks
The FDA label indicates 4-6 weeks for tinea capitis, but current guidelines recommend 6-8 weeks due to increasing treatment failures with shorter durations. 1, 4
Second-Line Options for Treatment Failure
If initial therapy fails, assess these factors: poor compliance, suboptimal drug absorption, organism insensitivity, or reinfection. 1, 3
If clinical improvement occurs but mycology remains positive: Continue current therapy for an additional 2-4 weeks. 1, 2, 3
If no clinical improvement occurs: Switch to second-line therapy. 1, 3
Second-line agents include: 1, 3
- Itraconazole: 5 mg/kg/day for 2-4 weeks (effective against both Trichophyton and Microsporum)
- Fluconazole: Favorable tolerability profile with liquid formulation available for younger children
Adjunctive Measures
Screen and treat family members and close contacts, especially for T. tonsurans infections where over 50% of household contacts may be affected. 1, 3
Use sporicidal shampoos (such as selenium sulfide) as adjunctive therapy to remove adherent scales and decrease spread. 1, 2
Clean all fomites with disinfectant or 2% sodium hypochlorite solution to prevent reinfection. 3
Critical Pitfalls to Avoid
Never use terbinafine for Microsporum infections—it has poor efficacy and will lead to treatment failure. 1, 2, 3
Never rely on topical therapy alone—it cannot eradicate scalp infections and is ineffective as monotherapy. 1, 2, 3
Avoid underdosing griseofulvin—higher doses (15-20 mg/kg/day rather than 10 mg/kg/day) are needed due to increasing treatment failures with lower doses. 1
Do not use Wood's lamp as your primary diagnostic tool—T. tonsurans (now the predominant organism in North America) is Wood's light negative. 5
Monitoring and Treatment Endpoint
The treatment endpoint is mycological cure, not just clinical improvement. 1, 2, 3 Repeat mycology sampling until clearance is achieved. 1, 2
Monitor for treatment side effects, though liver enzyme monitoring is generally unnecessary if therapy is limited to 4 weeks or less. 6
Children receiving appropriate therapy can attend school or nursery—they do not need to be excluded. 2, 3