What is the appropriate topical antifungal cream and regimen for treating typical skin ringworm (tinea corporis, tinea cruris, or tinea pedis)?

Topical Antifungal Treatment for Ringworm

For typical skin ringworm (tinea corporis, tinea cruris, or tinea pedis), apply terbinafine 1% cream twice daily for 1 week for tinea corporis/cruris or 1-2 weeks for tinea pedis, as this provides superior efficacy with the shortest treatment duration compared to other topical agents. 1, 2

First-Line Topical Therapy

Terbinafine 1% cream is the preferred initial treatment across all three conditions:

• Tinea corporis/cruris: Apply twice daily for 1 week 3
• Tinea pedis: Apply twice daily for 1-2 weeks 1, 2
• Achieves 84% mycological cure rate with once-daily application for 7 days in tinea corporis/cruris 3
• Superior to longer courses of other antifungal agents 1

Alternative Topical Options

If terbinafine is unavailable or not tolerated:

Ciclopirox olamine 0.77% cream/gel:

• Apply twice daily for 4 weeks 1, 2
• Achieves 60% cure at end of treatment, 85% cure two weeks post-treatment 1
• More effective than clotrimazole 1

Clotrimazole 1% cream:

• Apply twice daily for 2-4 weeks for tinea corporis/cruris 4, 5
• Apply twice daily for 4 weeks for tinea pedis 5
• Less effective than terbinafine but widely available over-the-counter 1

Ketoconazole 2% cream (FDA-approved):

• Apply once daily for 2 weeks for tinea corporis/cruris 6
• Apply once daily for 6 weeks for tinea pedis 6

Miconazole cream:

• Apply twice daily for 2-4 weeks 4

When to Use Oral Therapy

Reserve systemic antifungals for specific situations 1, 2:

• Extensive disease covering large body surface area
• Failed topical therapy after 2-4 weeks
• Concomitant onychomycosis (nail infection serves as reservoir) 1
• Immunocompromised patients 1
• Severe moccasin-type tinea pedis 7

Oral terbinafine 250 mg once daily:

• 1-2 weeks for tinea corporis/cruris 2, 8
• 1-2 weeks for tinea pedis 1, 2
• Provides faster clinical resolution than 4 weeks of topical clotrimazole 1
• Monitor for rare neutropenia and hepatic failure, especially with pre-existing liver disease 1

Oral itraconazole:

• 100 mg daily for 15 days (87% mycological cure) or 200 mg daily for 7 days for tinea corporis 4, 2
• 100 mg daily for 2 weeks or 400 mg daily for 1 week for tinea pedis 8
• Slightly higher relapse rate than terbinafine 1
• Important drug interactions with warfarin, antihistamines, antipsychotics, midazolam, digoxin, and simvastatin 4

Critical Prevention Measures to Prevent Recurrence

Environmental decontamination (often overlooked but essential):

• Discard old, moldy footwear when possible 1
• If shoes cannot be discarded: place naphthalene mothballs in shoes, seal in plastic bag for minimum 3 days, then air out 1
• Spray terbinafine solution inside shoes periodically 1
• Clean contaminated combs and brushes with disinfectant or 2% sodium hypochlorite 4

Personal hygiene:

• Thoroughly dry between toes after showering 1, 2
• Change to cotton, absorbent socks daily 1
• Apply antifungal foot powder after bathing (reduces infection rates from 8.5% to 2.1%) 1, 2
• Cover active foot lesions with socks before wearing underwear to prevent groin spread 1

Household management:

• Treat all infected family members simultaneously to prevent reinfection 1, 2
• Do not share towels, clothing, or personal items 2
• Avoid sharing toenail clippers 1

Common Pitfalls to Avoid

• Failing to examine for concomitant onychomycosis: Nail infection requires 12-16 weeks of oral terbinafine and serves as a reservoir for reinfection 1
• Neglecting footwear decontamination: Shoes harbor large numbers of viable dermatophyte spores causing recurrence 1
• Treating only the index patient: Over 50% of family members may be affected with anthropophilic species like Trichophyton tonsurans 4
• Stopping treatment at clinical clearing: Continue treatment for at least 1 week after clinical improvement to ensure mycological cure 5

Treatment Duration Summary

Condition	Topical Duration	Oral Duration
Tinea corporis	1-2 weeks (terbinafine) or 2-4 weeks (azoles) [5,3]	1-2 weeks [2,8]
Tinea cruris	1-2 weeks (terbinafine) or 2-4 weeks (azoles) [5,3]	1-2 weeks [2,8]
Tinea pedis	1-2 weeks (terbinafine) or 4-6 weeks (azoles) [1,6,5]	1-2 weeks [1,8]

Follow-Up Recommendations

• The definitive endpoint is mycological cure, not just clinical response 9, 2
• Repeat mycology sampling at end of treatment period, then monthly until mycological clearance documented 9
• If no clinical improvement after standard treatment period, redetermine diagnosis 6