What is the treatment for tinea capitis in adults?

Treatment of Tinea Capitis in Adults

Oral griseofulvin 15-20 mg/kg/day (or 500 mg to 1 g daily for adults >50 kg) for 6-8 weeks remains first-line treatment for tinea capitis in adults, with terbinafine 250 mg daily for 2-4 weeks as an effective alternative specifically for Trichophyton species infections. 1, 2

Mandatory Oral Therapy

• Oral antifungal therapy is absolutely required for tinea capitis—topical therapy alone is ineffective and not recommended 1, 2
• Treatment must be initiated based on organism identification or local epidemiology, as drug efficacy varies significantly by causative dermatophyte 1

First-Line Treatment Selection

Griseofulvin (Preferred for Microsporum species)

• Dosing for adults: 500 mg to 1 g daily (single or divided dose) for 6-8 weeks 1, 3
• More effective against Microsporum canis and M. audouinii infections 1, 2
• Requires 8 weeks of treatment for confirmed Microsporum infections, significantly more effective than shorter courses 1
• For Trichophyton infections, higher doses for longer periods (12-18 weeks) may be required due to reduced clinical efficacy 1
• Contraindications: lupus erythematosus, porphyria, severe liver disease 1, 2
• Drug interactions: plasma concentration decreased by rifampicin and increased by cimetidine 1

Terbinafine (Preferred for Trichophyton species)

• Dosing for adults >40 kg: 250 mg daily for 2-4 weeks 1, 2
• Superior efficacy against Trichophyton tonsurans, T. violaceum, and T. soudanense 1, 4, 2
• Shorter treatment duration improves compliance compared to griseofulvin 1, 2
• Critical limitation: Much lower efficacy against Microsporum species because terbinafine's minimum inhibitory concentration can exceed maximum concentration in hair, and it is not effectively incorporated into hair shafts, leading to treatment failures 1, 2
• Well tolerated with gastrointestinal disturbances and rashes in <8% of patients 1

Organism-Specific Treatment Algorithm

If Trichophyton species identified or suspected:

• Use terbinafine 250 mg daily for 2-4 weeks as first choice 1, 4, 2
• Alternative: griseofulvin 500 mg-1 g daily for 12-18 weeks (longer duration required) 1

If Microsporum species identified or suspected:

• Use griseofulvin 500 mg-1 g daily for 6-8 weeks as first choice 1, 2
• Avoid terbinafine due to poor efficacy 1, 2

Diagnostic Confirmation

• Collect specimens via scalpel scraping, hair pluck, brush, or swab before initiating treatment when possible 1, 2
• All specimens should be processed for both microscopy and culture 1
• In the presence of kerion or cardinal clinical signs (scale, lymphadenopathy, alopecia), it is reasonable to commence treatment while awaiting confirmatory mycology 1

Second-Line Therapy

Itraconazole

• Effective against both Trichophyton and Microsporum species 1
• Dosing: 100 mg daily for 15 days (based on tinea corporis data, extrapolated for tinea capitis) 4
• Important drug interactions: enhanced toxicity with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin 4

Fluconazole

• Third-line option with significant limitations 4
• Less cost-effective than terbinafine with limited comparative efficacy data 4
• Studies show 84% effective treatment rates for Trichophyton species when given at 6 mg/kg/day for 2-3 weeks 5

Management of Treatment Failure

Initial assessment should consider:

• Lack of compliance with medication regimen 1, 6, 2
• Suboptimal absorption of drug 1, 6, 2
• Relative insensitivity of the organism 1, 6, 2
• Reinfection from household contacts or fomites 1, 2

If clinical improvement but ongoing positive mycology:

• Continue current therapy for an additional 2-4 weeks 1, 6, 2

If no initial clinical improvement:

• Switch to second-line therapy (itraconazole) or alternate between terbinafine and griseofulvin based on organism 1, 2

Essential Adjunctive Measures

• Screen and treat all family members, as over 50% of household contacts may be affected with anthropophilic species like T. tonsurans 4, 2
• Clean all fomites (hairbrushes, combs, towels) with disinfectant or 2% sodium hypochlorite solution 4, 2
• Consider adjunctive sporicidal shampoos (selenium sulfide) to aid in removing adherent scales and decrease spread, though topical therapy alone is insufficient 7, 8

Treatment Endpoint and Monitoring

• Mycological cure, not just clinical response, is the definitive treatment endpoint 4, 2
• Medication must be continued until the infecting organism is completely eradicated as indicated by appropriate clinical or laboratory examination 3
• Clinical relapse will occur if medication is not continued until the organism is eradicated 3

Special Considerations for Adults

• Postmenopausal women, particularly African American or Black women, are at highest risk 9
• Adults with immunosuppression, crowded living conditions, close proximity to animals, or households with affected children are at greatest risk 9
• Delayed diagnosis or inadequate treatment can result in permanent scarring alopecia 9
• The prognosis is typically excellent when prompt and adequate treatment is administered 9