What is the recommended dose and duration of itraconazole (antifungal medication) for treating tinea (fungal) infections in adults and children?

Itraconazole Dosing for Tinea Infections

For tinea capitis (scalp ringworm), itraconazole is recommended as second-line therapy at 5 mg/kg/day (or 50-100 mg/day) for 2-4 weeks in children, while for tinea corporis and tinea cruris (body/groin ringworm), the standard adult dose is 100 mg daily for 15 days, and tinea pedis/manuum requires 100 mg daily for 30 days. 1, 2, 3

Tinea Capitis (Scalp Ringworm)

Children

• Itraconazole is positioned as second-line therapy when first-line agents (griseofulvin or terbinafine) fail 1
• Dosing: 5 mg/kg/day for 2-4 weeks (alternative: 50-100 mg/day for 4 weeks) 1
• Weight-based dosing for children ≤12 years: 6-10 mg/kg/day orally (maximum 400 mg daily) for cutaneous/lymphocutaneous infections 2
• The British Association of Dermatologists emphasizes that itraconazole is "safe, effective and has activity against both Trichophyton and Microsporum species" 1
• Clinical studies demonstrate 100% cure rates with 5 mg/kg/day for 4-8 weeks in Microsporum canis infections 4
• Pulse therapy is an effective alternative: 5 mg/kg/day for 1-week pulses, with 2-3 weeks between pulses; 81% cure rate after 1-3 pulses 5

Adults and Children >12 years

• Dosing: 200 mg twice daily 2
• Duration follows the same 2-4 week guideline as for younger children 1

Key Considerations for Tinea Capitis

• Treatment endpoint is mycological cure, not just clinical improvement—repeat mycology sampling until clearance is achieved 1
• Itraconazole oral solution should not be used interchangeably with capsules; capsules are generally ineffective for esophageal disease but appropriate for tinea capitis 2
• The drug demonstrates exceptional affinity for keratinized tissues with therapeutic concentrations persisting up to 4 weeks after discontinuation 6

Tinea Corporis and Tinea Cruris (Body and Groin Ringworm)

Adults

• Dosing: 100 mg daily for 15 days 3, 6
• This fixed schedule is based on pharmacokinetic studies showing tissue levels 10 times higher than plasma levels in sebaceous gland-rich areas 6
• Clinical response rates: 90% clinical improvement and 80% mycological cure 3-4 weeks after treatment completion 6
• Studies demonstrate significant symptom reduction within 2 weeks, with 83-89% negative cultures by 4-6 weeks 7

Children

• Weight-based dosing: 6-10 mg/kg/day orally (maximum 400 mg daily) 2
• Duration: 6-12 months for cutaneous fungal infections (though this appears to reference more severe/systemic cutaneous infections rather than simple tinea corporis/cruris) 2
• For uncomplicated tinea corporis/cruris in children, the 15-day adult regimen at appropriate weight-based dosing is reasonable 3

Tinea Pedis and Tinea Manuum (Foot and Hand Ringworm)

Adults

• Dosing: 100 mg daily for 30 days 3, 6
• The longer duration compared to tinea corporis/cruris reflects the thicker keratinized tissue and higher fungal burden in palmoplantar areas 6

Children

• Weight-based dosing: 6-10 mg/kg/day orally (maximum 400 mg daily) 2
• Duration should follow the 30-day adult guideline 3

Important Clinical Caveats

Formulation and Administration

• Capsules should be taken with food to enhance absorption 8
• Itraconazole cyclodextrin oral solution has different bioavailability and should not be substituted for capsules 2
• Serum levels should be determined after at least 2 weeks of therapy to ensure adequate drug exposure, particularly for severe infections 8

Drug Interactions

• Significant interactions occur via cytochrome P450 inhibition 8
• Enhanced toxicity with warfarin, certain antihistamines (terfenadine, astemizole), antipsychotics (sertindole), midazolam, digoxin, cisapride, ciclosporin, and simvastatin 1
• Decreased efficacy with H2 blockers, phenytoin, and rifampicin 1
• Caution required with protease inhibitors or non-nucleoside reverse transcriptase inhibitors in HIV-infected patients 2

Special Populations

• Pregnancy: Itraconazole should be avoided; amphotericin B is the preferred agent 2
• Not licensed in the UK for children ≤12 years with tinea capitis, though widely used off-label 1

Treatment Failure Management

• For tinea capitis treatment failures, initially consider non-compliance, suboptimal drug absorption, organism insensitivity, or reinfection 1
• If clinical improvement occurs but mycology remains positive, continue therapy for an additional 2-4 weeks 1
• If no initial clinical improvement, switch to alternative agents (terbinafine for Trichophyton, griseofulvin for Microsporum) 1

Monitoring

• The drug is generally well-tolerated with minimal adverse effects 3, 4, 5
• Laboratory monitoring is not routinely required unless indicated by history, examination, or development of side effects 4
• Rare hepatotoxicity has been reported; monitor if symptoms develop 7