What is the treatment for ringworm (tinea infection)?

Treatment for Ringworm (Tinea Infection)

For localized tinea corporis or tinea cruris, apply topical terbinafine 1% cream twice daily for 1-2 weeks, which provides superior efficacy compared to other topical agents and requires shorter treatment duration. 1, 2

Topical Therapy for Limited Skin Infections

First-Line Topical Treatment

• Terbinafine 1% cream applied twice daily for 1 week achieves 93.5% mycological cure rates, significantly superior to clotrimazole's 73.1% cure rate after 4 weeks of treatment 1
• Allylamines (terbinafine, naftifine) require only 1-2 weeks of treatment compared to 2-4 weeks for azoles 3, 2
• Naftifine 1% cream is also highly effective with a number needed to treat (NNT) of 3 for both mycological and clinical cure 2

Alternative Topical Agents

• Azole creams (clotrimazole, miconazole) applied twice daily for 2-4 weeks are effective but require longer treatment duration 3, 2
• Butenafine cream is another effective option for tinea corporis and cruris 4
• Continue treatment for at least 1 week after clinical clearing to prevent relapse 3

Important Caveat on Topical Steroids

• Combination antifungal/steroid creams show higher clinical cure rates at end of treatment but are NOT recommended in clinical guidelines due to potential for skin atrophy and other steroid complications 2
• Use combination products with extreme caution and only for severe inflammation 3

Oral Therapy Indications

When to Use Systemic Treatment

Oral antifungals are required for:

• Tinea capitis (scalp ringworm) - topical therapy alone is inadequate 5
• Extensive skin involvement not responding to topical therapy 6, 7
• Tinea unguium (nail infections) 7
• Failed topical treatment 4
• Immunocompromised patients 4

Oral Treatment Options for Tinea Corporis/Cruris

Terbinafine (preferred):

• 250 mg daily for 1-2 weeks, particularly effective against Trichophyton tonsurans 6, 8
• Shorter treatment duration compared to other agents 8

Itraconazole:

• 100 mg daily for 2 weeks OR 200 mg daily for 7 days 8
• 87% mycological cure rate for tinea corporis 6
• Important drug interactions: enhanced toxicity with warfarin, certain antihistamines (terfenadine, astemizole), antipsychotics, midazolam, digoxin, cisapride, and simvastatin 5, 6

Fluconazole (third-line):

• 50-100 mg daily for 2-3 weeks OR 150 mg once weekly for 2-3 weeks 8
• Less cost-effective than terbinafine with limited comparative data 6

Tinea Capitis Treatment Protocol

First-Line Systemic Therapy

Treatment selection depends on the causative organism - local epidemiology should guide initial choice 5:

For Trichophyton species (most common in UK/US):

• Terbinafine is superior:
  • <20 kg: 62.5 mg daily for 2-4 weeks
  • 20-40 kg: 125 mg daily for 2-4 weeks

  • 40 kg: 250 mg daily for 2-4 weeks 5

For Microsporum species:

• Griseofulvin remains treatment of choice:
  • 20-25 mg/kg daily for 6-8 weeks if <50 kg
  • 1 g daily for 6-8 weeks if >50 kg 5, 7
  • Take with fatty food to improve absorption 5

Adjunctive Topical Therapy

• Use antifungal shampoos (ketoconazole 2%, selenium sulfide 1%, or povidone-iodine) to reduce spore transmission, though they cannot cure the infection alone 5
• Apply 2-3 times weekly throughout treatment 5

Critical Management Points

• Start treatment immediately if kerion is present or diagnosis is clinically certain - do not wait for culture results 5
• The endpoint is mycological cure, not clinical improvement - continue follow-up with monthly cultures until clearance is documented 5
• Children can return to school once appropriate systemic therapy is started 5

Treatment Failure Management

Second-Line Therapy

If no clinical improvement after initial treatment:

• Switch from terbinafine to griseofulvin for Microsporum infections 5
• Switch from griseofulvin to terbinafine for Trichophyton infections 5
• Itraconazole 50-100 mg daily for 4 weeks OR 5 mg/kg daily for 2-4 weeks is effective for both Trichophyton and Microsporum species 5

If clinical improvement but persistent positive cultures:

• Continue current therapy for additional 2-4 weeks 5

Refractory Cases

• Consider fluconazole or voriconazole in exceptional circumstances 5
• Voriconazole is more potent but limited by cost and availability 5

Prevention and Screening

Essential Preventive Measures

• Screen and treat all family members and close contacts for Trichophyton tonsurans infections - over 50% may be affected 5, 6
• Clean contaminated combs, brushes, and towels with disinfectant or 2% sodium hypochlorite solution 5, 6
• Avoid skin-to-skin contact with infected individuals 6
• Do not share personal items (towels, clothing, sports equipment) 6
• Cover lesions during treatment 6

Asymptomatic Carriers

• Treat asymptomatic carriers with high spore loads using systemic antifungals to prevent transmission 5

Common Pitfalls to Avoid

• Do not diagnose tinea infections on clinical appearance alone - confirm with potassium hydroxide preparation or culture, especially for onychomycosis and tinea capitis 4
• Do not use topical therapy alone for tinea capitis - it will fail 5
• Do not stop treatment when lesions clear clinically - continue until mycological cure is achieved 5, 7
• Do not use griseofulvin as first-line for Trichophyton infections - terbinafine is superior 6
• Avoid combination steroid/antifungal creams except in severe inflammation due to risk of skin atrophy 3, 2