What is the treatment for ringworm infections?

Treatment of Ringworm (Tinea) Infections

For localized tinea corporis or tinea cruris, apply topical clotrimazole 1% or miconazole 2% cream twice daily for 2-4 weeks as first-line therapy; for extensive disease, tinea capitis, or treatment failure, use oral terbinafine 250 mg daily for 1-2 weeks (tinea corporis/cruris) or 4-6 weeks (tinea capitis). 1, 2, 3

First-Line Topical Therapy for Localized Disease

Topical antifungals are appropriate for tinea corporis and tinea cruris when lesions are limited and not involving hair follicles:

• Clotrimazole 1% cream applied twice daily for 2-4 weeks is effective for ringworm under the axilla and other body sites 1
• Miconazole 2% cream applied twice daily for 2-4 weeks is an equally effective alternative 1
• Topical therapy alone is generally sufficient for tinea corporis and tinea cruris when disease is not extensive 3, 4
• Terbinafine topical formulations demonstrate superior efficacy compared to placebo (RR 4.51,95% CI 3.10-6.56, NNT 3) 4
• Naftifine 1% is also highly effective with mycological cure rates significantly better than placebo (RR 2.38,95% CI 1.80-3.14, NNT 3) 4

Oral Therapy Indications

Systemic antifungals are required in specific clinical scenarios:

• Tinea capitis (scalp ringworm) always requires oral therapy because topical agents cannot adequately penetrate hair follicles 2, 3
• Extensive tinea corporis or tinea cruris involving large body surface areas 3, 5
• Lack of response to appropriate topical treatment after 2 weeks 1
• Immunocompromised patients 3
• Tinea pedis with hyperkeratosis unresponsive to topical monotherapy 5
• Tinea unguium (onychomycosis) 2, 3

Oral Antifungal Regimens

Terbinafine is first-line oral therapy for most dermatophyte infections:

• For tinea corporis/cruris: 250 mg daily for 1-2 weeks 6
• For tinea capitis: 250 mg daily for 4-6 weeks (adults); pediatric dosing 10 mg/kg daily 2, 3
• For tinea pedis: 250 mg daily for 2 weeks 6
• Terbinafine is well-tolerated, effective, and inexpensive, making it the preferred oral agent 3

Alternative oral regimens when terbinafine is contraindicated or ineffective:

• Itraconazole 100 mg daily for 2 weeks or 200 mg daily for 7 days for tinea corporis/cruris 6
• Itraconazole 200 mg daily or higher for longer duration for emerging resistant strains like Trichophyton indotineae 7
• Fluconazole 150-200 mg weekly for 2-4 weeks for extensive or resistant cases 1, 6
• Griseofulvin 500 mg daily (adults) or 10 mg/kg daily (pediatrics >2 years) for 2-4 weeks (tinea corporis) or 4-6 weeks (tinea capitis) 2

Treatment Duration by Site

Medication must continue until complete eradication of the organism:

• Tinea capitis: 4-6 weeks 2
• Tinea corporis: 2-4 weeks 2, 4
• Tinea pedis: 4-8 weeks 2
• Tinea unguium (fingernails): at least 4 months 2
• Tinea unguium (toenails): at least 6 months 2

Critical Pitfalls to Avoid

Common errors that compromise treatment outcomes:

• Never use combination antifungal-corticosteroid creams as first-line therapy - while they may provide faster symptom relief, they can mask infection, promote spread, and contribute to antifungal resistance 3
• Do not rely on clinical diagnosis alone - confirm with KOH preparation, fungal culture, or nail biopsy before initiating treatment 2, 3
• Avoid premature discontinuation - clinical improvement precedes mycological cure; stopping treatment early leads to relapse 2
• Do not use topical therapy for tinea capitis - it causes irritation and cannot reach organisms in hair follicles 5
• Griseofulvin is not effective against Candida, bacteria, or non-dermatophyte fungi - ensure correct diagnosis 2
• Terbinafine is ineffective for pityriasis versicolor (a yeast infection, not dermatophyte) 6

Emerging Resistant Infections

New treatment considerations for Trichophyton indotineae and other resistant strains:

• T. indotineae shows poor response to terbinafine due to squalene epoxidase gene mutations 7
• For terbinafine-resistant infections, use itraconazole 200 mg/day or higher for extended duration 7
• Fluconazole and griseofulvin are generally ineffective against T. indotineae 7
• When both terbinafine and itraconazole fail, consider off-label voriconazole or posaconazole 7
• Topical non-allylamine antifungals may be used as monotherapy for small areas or combined with oral therapy 7

Monitoring and Switching Therapy

If no improvement after 2 weeks of appropriate therapy, switching to a different antifungal class is necessary 1

• Reassess diagnosis with repeat microscopy or culture 2
• Consider compliance issues, reinfection sources, or resistant organisms 7
• Implement hygiene measures to control sources of infection or reinfection 2
• Concomitant topical therapy is usually required for tinea pedis even with oral treatment 2