What is the first‑line treatment for tinea corporis in an otherwise healthy adult or adolescent, and when should oral antifungal therapy be initiated?

Treatment of Tinea Corporis in Healthy Adults and Adolescents

Topical terbinafine 1% cream applied once daily for 1-2 weeks is the first-line treatment for localized tinea corporis in otherwise healthy adults and adolescents. 1, 2

First-Line Topical Therapy

Allylamine agents (terbinafine or naftifine) are preferred over azoles because they require shorter treatment duration and demonstrate superior efficacy. 1, 2

• Terbinafine 1% cream once daily for 1-2 weeks is the most strongly recommended topical agent 1, 2
• Naftifine 1% once daily for 1-2 weeks is an effective alternative allylamine option 1
• Azole alternatives (clotrimazole, miconazole) require twice-daily application for 2-4 weeks, making them less convenient 3, 4

Topical therapy alone is appropriate when the infection is localized with limited skin involvement in immunocompetent patients without prior treatment failure. 2

When to Initiate Oral Antifungal Therapy

Oral antifungal therapy should be initiated when:

• The infection is extensive or covers a large body surface area 1, 2
• Topical treatment has failed after an adequate trial 3, 2
• The patient is immunocompromised 1, 5
• The infection is resistant to initial topical therapy 3, 6
• Multiple lesions are present or the infection is deep, recurrent, or chronic 6

Oral Antifungal Options

Terbinafine 250 mg daily for 1-2 weeks is the first-line oral agent, achieving an 87.1% mycological cure rate. 1, 2

• Terbinafine demonstrates particularly high activity against Trichophyton tonsurans infections, the most common anthropophilic dermatophyte in the UK and US 2
• Itraconazole 100 mg daily for 15 days is an effective alternative, achieving an 87% mycological cure rate 3, 1, 2
• Itraconazole is superior to griseofulvin (87% vs 57% cure rate) 3, 2

Griseofulvin should not be used as first-line therapy due to longer treatment duration and lower efficacy compared to terbinafine. 3, 2

Diagnostic Confirmation Before Treatment

Obtain potassium hydroxide (KOH) preparation or fungal culture before initiating treatment to confirm dermatophyte infection and identify the causative organism. 1, 2

• This is particularly important because tinea corporis has many clinical mimics including eczema 5
• Culture on Sabouraud agar if KOH is negative but clinical suspicion remains high 1
• Dermoscopy is a useful non-invasive diagnostic tool when the diagnosis is uncertain 6

Treatment Monitoring and Endpoints

Mycological cure (negative microscopy and culture), not just clinical response, is the definitive treatment endpoint. 1, 2

• Continue treatment for at least one week after clinical clearing of infection 4
• Repeat mycology sampling at the end of standard treatment period and continue monthly until mycological clearance is documented 1
• Follow-up should include both clinical and mycological assessment 3

Prevention of Recurrence

Screen and treat all household contacts, as over 50% of family members may be affected with anthropophilic species like T. tonsurans. 1, 2

Essential preventive measures include:

• Avoid direct skin-to-skin contact with infected individuals and keep active lesions covered 1, 2
• Do not share towels, combs, brushes, or other personal items 3, 2
• Clean all fomites (combs, brushes, towels, clothing) with disinfectant or 2% sodium hypochlorite solution 3, 1, 2
• Apply antifungal powders (miconazole, clotrimazole, tolnaftate) to prevent reinfection in high-risk individuals 1

Important Safety Considerations

Obtain baseline liver function tests before initiating oral terbinafine or itraconazole, especially in patients with pre-existing hepatic abnormalities. 3, 1

• Avoid itraconazole in patients with heart failure due to significant drug interactions 1
• Itraconazole has important drug interactions with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin 3
• Adverse effects with topical agents are generally mild (irritation, burning) and reported infrequently 7

Management of Treatment Failure

If initial therapy fails, assess compliance, drug absorption, and potential reinfection sources. 1

• Continue current therapy for an additional 2-4 weeks if clinical improvement occurs but mycology remains positive 1
• Switch to alternative oral agent: use itraconazole if terbinafine failed, or terbinafine if azole failed 1
• Consider terbinafine resistance in cases of recurrent, therapy-refractory dermatophytoses caused by T. rubrum 8

Special Populations: Athletes

Athletes with tinea corporis should complete at least 72 hours of topical or systemic antifungal therapy and keep lesions covered with a gas-permeable dressing before resuming competition activities. 1