What is the first‑line treatment for ringworm (tinea corporis, tinea cruris, tinea pedis, or tinea capitis) in an otherwise healthy adult with localized skin lesions?

First-Line Treatment for Ringworm (Tinea Corporis, Tinea Cruris, Tinea Pedis)

Topical Antifungal Therapy for Localized Disease

For otherwise healthy adults with localized tinea corporis, tinea cruris, or tinea pedis, topical antifungal therapy is the first-line treatment, with terbinafine or azoles (clotrimazole, miconazole, ketoconazole) applied for 2-4 weeks. 1, 2, 3

Specific Topical Regimens

Preferred topical agents include:

• Terbinafine 1% cream or gel applied once daily for 1-2 weeks for tinea corporis and tinea cruris 1, 2
• Clotrimazole 1% cream applied twice daily for 2-4 weeks 1
• Miconazole cream applied twice daily for 2-4 weeks 1
• Ketoconazole 2% cream applied once daily for 2 weeks for tinea corporis and tinea cruris 4
• Naftifine 1% cream applied twice daily, which shows superior efficacy compared to placebo (RR 2.38 for mycological cure) 5

For tinea pedis specifically, treatment duration should be extended to 4-6 weeks to reduce recurrence risk, as this site requires longer therapy than tinea corporis or cruris 4, 6

Advantages of Allylamines vs Azoles

Terbinafine (an allylamine) offers practical advantages over azoles: it requires fewer applications and shorter treatment duration (1-2 weeks vs 2-4 weeks), which improves adherence 6, 5. The evidence shows terbinafine achieves significantly higher clinical cure rates compared to placebo (RR 4.51, NNT 3) 5.

Oral Antifungal Therapy for Extensive or Resistant Disease

Oral antifungal therapy is indicated when:

• The infection is extensive or covers large body surface areas 1, 2, 3
• Topical treatment has failed 1, 3
• Hair follicles are involved 3
• The patient is immunocompromised 3

Oral Treatment Options

For tinea corporis and tinea cruris:

• Terbinafine 250 mg daily for 1-2 weeks is particularly effective against Trichophyton species (the most common causative organism) 1, 2, 7
• Itraconazole 100 mg daily for 15 days achieves 87% mycological cure rate and is effective against both Trichophyton and Microsporum species 1, 2, 7
• Fluconazole 150 mg once weekly for 2-4 weeks is an alternative option 7, 8

For tinea pedis:

• Terbinafine 250 mg daily for 2 weeks 7
• Itraconazole 100 mg daily for 2 weeks or 400 mg daily for 1 week 7
• Fluconazole 150 mg once weekly as pulse dosing 7

Important Safety Monitoring

Baseline liver function tests are recommended before initiating terbinafine or itraconazole, especially in patients with pre-existing hepatic abnormalities or when prolonged therapy is anticipated 1, 2. Itraconazole has significant drug interactions with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin that must be considered 2.

Special Consideration: Tinea Capitis Requires Different Approach

Tinea capitis always requires systemic therapy because topical agents cannot penetrate hair follicles adequately 2, 3. For adults with tinea capitis:

• Terbinafine 250 mg daily for 2-4 weeks is preferred for Trichophyton species 2, 9
• Griseofulvin 1 g/day for 6-8 weeks is preferred for Microsporum species 2, 9

Treatment Endpoints and Follow-Up

The definitive endpoint for adequate treatment must be mycological cure (negative microscopy and culture), not just clinical improvement 1, 2. Treatment should continue for at least one week after clinical clearing of infection 6. If clinical improvement occurs but mycology remains positive, continue therapy for an additional 2-4 weeks 2.

Critical Pitfalls to Avoid

Avoid combination antifungal-corticosteroid creams as first-line therapy. While some studies show higher initial clinical cure rates with combination products, they should be used with extreme caution due to potential for skin atrophy, steroid-associated complications, and concerns about promoting antifungal resistance 6, 3, 5. The evidence for combination products was rated very low quality due to imprecision and risk of bias 5.

Do not use topical therapy alone for tinea capitis - this will fail as topical agents cannot adequately treat hair follicle involvement 2, 3.

Prevention of Recurrence

Implement these measures to prevent reinfection:

• Avoid skin-to-skin contact with infected individuals 1
• Do not share towels, clothing, or personal items 1
• Wear protective footwear in public bathing facilities, gyms, and hotel rooms 2
• Apply antifungal powders (miconazole, clotrimazole, or tolnaftate) to feet and in shoes for tinea pedis 2
• Clean contaminated combs and brushes with disinfectant 1, 9
• Screen and treat family members if anthropophilic species are identified 1, 2