What is the appropriate first‑line treatment for uncomplicated cutaneous ringworm (tinea corporis, tinea cruris, or tinea pedis)?

Treatment of Uncomplicated Cutaneous Ringworm

For uncomplicated tinea corporis, tinea cruris, or 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 of any topical antifungal. 1, 2, 3

First-Line Topical Therapy

Terbinafine (Preferred Agent)

• Terbinafine 1% cream applied twice daily for 1 week achieves approximately 94% mycological cure for tinea corporis and tinea cruris 2
• For tinea pedis, terbinafine 1% cream applied twice daily for 1 week is more effective than longer courses of other antifungal agents 1
• The major advantage is the much shorter treatment duration (1 week versus 4 weeks for azoles), which significantly improves adherence 2, 4
• Terbinafine has fungicidal rather than fungistatic action against dermatophytes, allowing for shorter treatment courses 1, 4
• FDA-approved for athlete's foot, jock itch, and ringworm with relief of itching, burning, cracking, and scaling 3

Alternative Topical Agents (If Terbinafine Unavailable)

• Ciclopirox olamine 0.77% cream/gel applied twice daily for 4 weeks achieves approximately 60% cure at end of treatment and 85% cure two weeks after completion 1, 2
• Clotrimazole 1% cream applied twice daily for 4 weeks is less effective than both terbinafine and ciclopirox but remains widely available over-the-counter 1
• Other azole antifungals (miconazole, ketoconazole) applied twice daily for 2-4 weeks are effective alternatives 5, 6

When to Use Oral Antifungal Therapy

Oral therapy should be reserved for specific clinical scenarios rather than routine uncomplicated infections. 1, 7

Indications for Oral Treatment

• Extensive or widespread infection involving large body surface areas 7, 2
• Hair follicle involvement (folliculitis) 7
• Failed topical therapy after 4 weeks of appropriate treatment 1, 7, 2
• Concomitant onychomycosis (nail infection serves as a reservoir for reinfection) 1
• Immunocompromised patients 1, 7, 2
• Chronic or deep tissue infection 2

Oral Treatment Options

• Terbinafine 250 mg once daily for 1-2 weeks is first-line oral therapy, with over 70% oral absorption and fungicidal action 1
• Itraconazole 100 mg daily for 15 days achieves 87% mycological cure but has slightly higher relapse rates than terbinafine 1, 7, 2
• Terbinafine is superior for Trichophyton species (the most common dermatophyte), while itraconazole has broader spectrum including Candida 1, 7

Critical Prevention Measures to Avoid Recurrence

Address Environmental Reservoirs

• Examine for and treat concomitant onychomycosis, as nail infection requires 12-16 weeks of oral terbinafine and serves as a major reservoir for reinfection 1
• Clean or discard contaminated footwear, as shoes harbor large numbers of viable dermatophyte spores 1
• If shoes cannot be discarded, seal with naphthalene mothballs in a plastic bag for minimum 3 days, then air out 1
• Spray terbinafine solution inside shoes periodically 1

Personal Hygiene Measures

• Thoroughly dry affected areas (especially between toes and skin folds) after bathing 1, 2
• Change to clean, cotton, absorbent socks daily (reduces infection rates from 8.5% to 2.1%) 1
• Apply antifungal foot powder after bathing for tinea pedis 1
• Avoid sharing towels, clothing, or personal items 7
• Cover active lesions to prevent spread 7

Household Management

• Treat all infected family members simultaneously to prevent reinfection cycles 1, 7
• Clean contaminated combs and brushes with disinfectant 7
• For tinea pedis, put on socks before underwear to prevent spread to groin 1

Common Pitfalls to Avoid

• Do NOT use combination antifungal-corticosteroid creams as first-line therapy - while they may provide faster symptom relief, they can cause skin atrophy, mask infection, and promote resistance 8, 5
• Do NOT stop treatment when symptoms resolve - continue for at least 1 week after clinical clearing to ensure mycological cure 7, 6
• Do NOT fail to examine the entire skin surface - dermatophytes commonly cause concomitant infections at multiple body sites (hands, groin, body folds) requiring simultaneous treatment 1
• Do NOT neglect footwear decontamination - this is a major source of recurrence 1
• The treatment endpoint should be mycological cure, not just clinical improvement 7, 2

Monitoring and Follow-Up

• Follow-up should include both clinical and mycological assessment 7
• For oral terbinafine in patients with liver disease history, obtain baseline liver function tests and complete blood count 1
• Common adverse effects of oral terbinafine 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