What is the recommended management of ringworm (tinea infection), including first‑line topical therapy, dosing and duration, and special considerations for children, pregnancy, extensive disease, and nail or scalp involvement?

Management of Ringworm (Tinea Infections)

First-Line Treatment by Anatomical Site

For localized tinea corporis, tinea cruris, and tinea pedis, topical antifungal therapy is the recommended first-line treatment, while tinea capitis and tinea unguium always require oral systemic therapy. 1

Topical Therapy for Skin Infections (Corporis, Cruris, Pedis)

Recommended topical agents and durations:

• Terbinafine 1% cream or gel: Apply once daily for 1-2 weeks 2, 1, 3

  • Superior efficacy due to fungicidal mechanism of action 3
  • Particularly effective against Trichophyton species 2, 1

• Clotrimazole cream: Apply twice daily for 2-4 weeks 2

• Miconazole cream: Apply twice daily for 2-4 weeks 2

• Alternative agents: Ciclopirox 0.77% cream/gel twice daily for 4 weeks, or naftifine ointment twice daily for 4 weeks 1

Treatment should continue for at least one week after clinical clearing to ensure mycological cure. 4

Oral Therapy Indications for Skin Infections

Systemic antifungal therapy is indicated when: 2, 1, 5

• Infection is extensive or covers large body surface area
• Topical treatment has failed
• Patient is immunocompromised
• Hair follicle involvement is present

Oral treatment options for extensive skin infections:

• Terbinafine 250 mg daily for 1-2 weeks 2, 1

  • Mycological cure rate of 86% at 8 weeks 1
  • Shorter treatment duration improves compliance 6

• Itraconazole 100 mg daily for 15 days 2, 1

  • Mycological cure rate of 87% 2, 1
  • Effective against both Trichophyton and Microsporum species 1, 6

Tinea Capitis: Organism-Directed Oral Therapy Required

Oral systemic antifungal therapy is mandatory for tinea capitis; topical therapy alone is completely ineffective and should never be used as monotherapy. 1, 6

First-Line Treatment Based on Causative Organism

For Trichophyton species (most common in North America): 1, 6

• Terbinafine (preferred): 1, 6
  • Children <20 kg: 62.5 mg daily for 2-4 weeks
  • Children 20-40 kg: 125 mg daily for 2-4 weeks
  • Children >40 kg and adults: 250 mg daily for 2-4 weeks
  • Superior efficacy with shorter treatment duration 6

For Microsporum species: 1, 6

• Griseofulvin (preferred): 1, 6
  • Children <50 kg: 15-20 mg/kg/day for 6-8 weeks
  • Children >50 kg and adults: 1 g/day for 6-8 weeks
  • Eight weeks significantly more effective than shorter courses for Microsporum 6
  • Only licensed treatment for tinea capitis in children in many countries 6

Critical point: Terbinafine fails against Microsporum species because it cannot be incorporated into hair shafts in prepubertal children. 6

When to Start Treatment Empirically

Begin treatment immediately without waiting for culture results if any of these cardinal signs are present: 6

• Scaling of the scalp
• Lymphadenopathy
• Alopecia (hair loss)
• Kerion (inflammatory, boggy mass)

Second-Line Options for Treatment Failure

If initial therapy fails, consider: 6

• Itraconazole: 5 mg/kg/day for 2-4 weeks or 50-100 mg/day for 4 weeks 6

  • Effective against both Trichophyton and Microsporum species 6
  • Licensed for children over 12 years in UK, used off-label in younger children 2

• Fluconazole: Alternative for refractory cases with favorable tolerability and liquid formulation available 6

If clinical improvement occurs but mycology remains positive, continue current therapy for an additional 2-4 weeks; if no clinical improvement, switch to second-line therapy. 1, 6

Adjunctive Measures for Tinea Capitis

Mandatory additional interventions: 6

• Use topical antifungal shampoo (ketoconazole or selenium sulfide) as adjunctive therapy only, not monotherapy 6
• Screen and treat all family members and close contacts, especially for T. tonsurans infections (>50% of family members may be affected) 2, 6
• Clean hairbrushes and combs with bleach or 2% sodium hypochlorite solution 6
• Children receiving appropriate systemic and adjunctive topical therapy can attend school; exclusion is unnecessary 6

Special Consideration: Kerion Management

For kerion (inflammatory, boggy scalp mass): 6

• Initiate oral systemic antifungal therapy immediately 6
• Add topical or oral corticosteroids to alleviate severe inflammatory symptoms 6
• Recognize that kerion represents a fungal-driven inflammatory response, not bacterial abscess (though evaluate for secondary bacterial infection when clinically indicated) 6

Tinea Unguium (Onychomycosis): Oral Therapy Required

Oral antifungal therapy is the treatment of choice for nail infections, with terbinafine generally preferred over itraconazole due to superior efficacy and shorter treatment duration. 1

Recommended regimens: 1

• Terbinafine 250 mg daily (preferred):

  • Fingernail infections: 6 weeks
  • Toenail infections: 12-16 weeks

• Itraconazole (alternative):

  • Continuous therapy: 200 mg daily for 12 weeks
  • Pulse therapy: 400 mg daily for 1 week per month (2 pulses for fingernails, 3 pulses for toenails)

Special Populations

Children

• Weight-based dosing is essential for tinea capitis (see organism-directed therapy above) 1, 6
• Terbinafine has gastrointestinal disturbances and rashes in <8% of children 6
• Griseofulvin is the only FDA-approved agent for tinea capitis in children in many jurisdictions 6, 7

Pregnancy

• Avoid systemic antifungals when possible; use topical therapy for localized skin infections 5
• If systemic therapy is absolutely necessary, consult with obstetrics and consider risk-benefit carefully (evidence does not provide specific pregnancy recommendations, but general medical practice favors avoiding systemic antifungals)

Critical Monitoring and Treatment Endpoints

The definitive endpoint for adequate treatment must be mycological cure (negative microscopy and culture), not just clinical improvement. 2, 1, 6

Monitoring protocol: 2, 1, 6

• Obtain baseline liver function tests before initiating terbinafine or itraconazole, especially with pre-existing hepatic abnormalities 2, 1
• Perform repeat mycology sampling at the end of standard treatment period 1
• Continue monthly sampling until mycological clearance is documented 1
• Monitor for treatment side effects, particularly hepatotoxicity with prolonged therapy 1

Prevention of Recurrence

Essential preventive measures: 2, 1

• Avoid skin-to-skin contact with infected individuals 2
• Do not share towels, clothing, hairbrushes, or other personal items 2
• Cover lesions during treatment 2
• Wear protective footwear in public bathing facilities, gyms, and hotel rooms 1
• Apply antifungal powders (miconazole, clotrimazole, or tolnaftate) in shoes and on feet for tinea pedis 1
• Clean all fomites with disinfectant or 2% sodium hypochlorite solution 2

Common Pitfalls to Avoid

Critical errors in management: 2, 6, 5

• Never use terbinafine for Microsporum infections - it has poor efficacy due to inability to reach the infection site in prepubertal children 6
• Never use topical therapy alone for tinea capitis - it cannot eradicate scalp infections 6
• Never use combination antifungal-corticosteroid agents routinely - they can cause atrophy and promote resistance; reserve for severe inflammation only 4, 5
• Never stop antifungal therapy based on clinical improvement alone - continue until mycological cure is documented 2, 1, 6
• Never underdose griseofulvin - treatment failures are increasing with lower doses 6

Important Drug Interactions

Itraconazole has significant drug interactions: 2, 1

• Enhanced toxicity with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, cisapride, and simvastatin
• Contraindicated in heart failure 1