What is the recommended treatment for ringworm (tinea corporis, tinea cruris, tinea pedis, or tinea barbae)?

Treatment of Ringworm (Tinea Infections)

For most cases of tinea corporis, tinea cruris, and tinea pedis, topical terbinafine 1% cream applied once or twice daily for 1 week is the first-line treatment, offering superior efficacy with the shortest treatment duration. 1, 2, 3

First-Line Topical Therapy

Terbinafine (Preferred)

• Topical terbinafine 1% cream applied twice daily for 1 week achieves approximately 94% mycological cure for tinea corporis and tinea cruris, significantly outperforming other topical agents 4, 3
• For tinea pedis (interdigital type), terbinafine 1% cream twice daily for 1 week achieves 66% effective treatment, compared to only 4% with vehicle 1, 2
• The major advantage is the much shorter treatment duration (1 week vs 4 weeks for other agents), which dramatically improves patient adherence 1, 4
• Terbinafine has fungicidal properties against dermatophytes, allowing for sustained cure rates even after short treatment courses 3

Alternative Topical Agents

• Ciclopirox olamine 0.77% cream/gel applied twice daily for 4 weeks achieves approximately 60% clinical and mycological cure at end of treatment, rising to 85% two weeks post-treatment 1
• Clotrimazole 1% cream applied twice daily for 4 weeks is less effective than terbinafine but widely available over-the-counter 1
• Ketoconazole 2% cream is FDA-approved for tinea corporis, tinea cruris, and tinea pedis caused by Trichophyton rubrum, T. mentagrophytes, and Epidermophyton floccosum 5
• Topical therapy should continue for at least one week after clinical clearing to prevent relapse 6

Oral Therapy Indications

Reserve oral antifungal agents for specific situations where topical therapy is inadequate or inappropriate. 1, 7

When to Use Oral Therapy

• Extensive disease covering large body surface areas 1, 7
• Failed topical therapy after 4 weeks 4
• Chronic or deep tissue involvement 1
• Concomitant onychomycosis (nail infection serves as reservoir for reinfection) 1
• Immunocompromised patients 1, 7
• Hair follicle involvement (tinea capitis or tinea barbae) 7

Oral Treatment Options

Terbinafine (First-Line Oral Agent)

• Oral terbinafine 250 mg once daily for 1-2 weeks is the most effective oral treatment for tinea corporis, cruris, and pedis, with fungicidal action allowing shorter treatment duration 1, 8
• Terbinafine has higher efficacy against dermatophytes than itraconazole, with lower minimum inhibitory concentrations 1
• Over 70% oral absorption unaffected by food intake 1
• For tinea pedis requiring oral therapy, extend treatment to 2 weeks at 250 mg daily 1, 8

Itraconazole (Alternative)

• Itraconazole 100 mg daily for 2 weeks has similar mycological efficacy to terbinafine but may have slightly higher relapse rates 1, 8
• Alternative dosing: 200 mg daily for 7 days or pulse dosing at 200-400 mg per day for 1 week per month 1, 8
• Broader antifungal spectrum than terbinafine, covering Candida species and non-dermatophyte moulds 1

Fluconazole (Less Effective)

• Fluconazole is less effective than both terbinafine and itraconazole for dermatophyte infections and should be reserved for cases where other agents are contraindicated 1
• Dosing: 150 mg once weekly for 2-3 weeks, or 50-100 mg daily for 2-3 weeks 8
• Advantage: fewer drug interactions due to weaker cytochrome P450 inhibition 1

Griseofulvin (Not Recommended First-Line)

• Griseofulvin is FDA-approved for tinea corporis, tinea cruris, and tinea pedis but is not recommended as first-line therapy due to lower efficacy (30-40% cure rates) and longer treatment duration 9, 1
• May be considered when other drugs are unavailable or contraindicated 10
• Prior to therapy, dermatophyte identification should confirm the organism is responsible for infection 9

Critical Prevention and Management Strategies

Preventing Recurrence

• Thoroughly dry between toes and in skin folds after bathing to reduce moisture that promotes fungal growth 1
• Apply antifungal foot powder after bathing, which reduces tinea pedis rates from 8.5% to 2.1% 1
• Change to cotton, absorbent socks daily 1
• Treat all infected family members simultaneously to prevent reinfection cycles 1

Addressing Footwear Contamination

• Contaminated footwear is a major source of reinfection because shoes harbor large numbers of viable dermatophyte spores 1
• Discard old, moldy footwear when possible 1
• If shoes cannot be discarded, place naphthalene mothballs in shoes and seal in plastic bag for minimum 3 days, then air out 1
• Spray terbinafine solution inside shoes periodically for additional antifungal protection 1
• Apply antifungal powders containing miconazole, clotrimazole, or tolnaftate inside shoes 1

Examining for Concomitant Infections

• Always examine for concomitant onychomycosis (nail infection), which requires extended oral terbinafine therapy (12-16 weeks) and acts as a reservoir for skin reinfection 1
• Cover active foot lesions with socks before wearing underwear to prevent spread to groin area 1
• Dermatophyte organisms can spread to distant sites via direct contact or contaminated hands, so examine hands, groin, and body folds 1

Safety Monitoring for Oral Terbinafine

• Baseline liver function tests (LFTs) and complete blood count (CBC) are recommended before initiating oral terbinafine in adults with history of hepatotoxicity or hematologic abnormalities 1
• Common adverse effects include headache, taste disturbance, and gastrointestinal upset 1
• Rare but serious adverse events include isolated neutropenia and hepatic failure, particularly in patients with pre-existing liver disease 1

Common Pitfalls to Avoid

• Failing to confirm diagnosis with KOH preparation or fungal culture before treatment, as other conditions (eczema, psoriasis) can mimic tinea infections 7
• Treating only clinical improvement rather than mycological cure, which leads to relapse 4
• Using combination antifungal-corticosteroid agents routinely, which should be avoided per antifungal stewardship principles 7
• Neglecting to examine and treat family members, allowing reinfection 1
• Stopping treatment when symptoms resolve rather than completing the full course and continuing one week after clinical clearing 6