What is the recommended treatment for ringworm (tinea corporis)?

Treatment of Ringworm (Tinea Corporis)

First-Line Treatment: Topical Antifungals

For localized tinea corporis, topical antifungal therapy is the first-line treatment, with oral antifungals reserved for extensive infections, treatment failures, or immunocompromised patients. 1

Topical Regimen Options

Allylamine agents (preferred for shorter duration):

• Terbinafine cream applied once or twice daily for 1-2 weeks 1
• Naftifine cream applied once or twice daily for 1-2 weeks 1
• These offer the advantage of shorter treatment duration compared to azoles 1

Azole agents (alternative, longer duration):

• Clotrimazole cream applied twice daily for 2-4 weeks 2
• Miconazole cream applied twice daily for 2-4 weeks 2

The allylamines are generally preferred because they require only 1-2 weeks of treatment versus 2-4 weeks for azoles, improving adherence while maintaining equivalent efficacy 1, 3. Evidence shows terbinafine achieves significantly higher clinical cure rates compared to placebo (RR 4.51, NNT 3) 4.

Oral Antifungal Therapy

Oral therapy is indicated when:

• The infection is extensive or covers large body surface areas 1
• Topical treatment has failed 2, 1
• The patient is immunocompromised 1
• Hair follicles are involved 5

Oral Treatment Options (in order of preference)

First-line oral agent:

• Terbinafine 250 mg daily for 1-2 weeks 2, 1
• Particularly effective against Trichophyton tonsurans, T. rubrum, and T. mentagrophytes 2, 1
• Achieves 87.1% mycological cure rate at 6-week follow-up 1
• Well tolerated with minimal drug interactions compared to azoles 1
• One study demonstrated 100% mycological cure with just 1 week of therapy 6

Second-line oral agent:

• Itraconazole 100 mg daily for 15 days 2, 1
• Achieves 87% mycological cure rate, superior to griseofulvin's 57% 1
• Licensed for children over 12 years in the UK 2
• Requires caution due to significant drug interactions with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, and simvastatin 2, 1
• Baseline liver function tests recommended before initiating therapy 2

Third-line (not recommended as first-line):

• Griseofulvin is NOT recommended as first-line treatment due to longer treatment duration (2-4 weeks for tinea corporis), lower efficacy than terbinafine, and lower cure rates 2, 7
• Fluconazole has significant limitations including not being licensed for tinea in children under 10 years in the UK and being less cost-effective than terbinafine 2

Critical Diagnostic Considerations Before Treatment

Confirm the diagnosis before initiating therapy:

• Perform potassium hydroxide (KOH) preparation or fungal culture to identify the causative dermatophyte 1, 7
• Collect specimens via scalpel scraping, hair pluck, brush, or swab as appropriate 2
• Clinical diagnosis alone is unreliable as other conditions (eczema, psoriasis) can mimic tinea corporis 5

Treatment Monitoring and Success Criteria

Mycological cure, not just clinical response, is the definitive treatment endpoint. 1, 8

• Continue treatment for at least one week after clinical clearing of infection 3
• Follow-up with repeat mycology sampling until clearance is documented 2, 1
• If clinical improvement occurs but mycology remains positive, continue current therapy for an additional 2-4 weeks 1, 8
• If no clinical improvement, switch to second-line therapy 8

Prevention of Recurrence (Essential Component)

Screen and treat all family members, as over 50% of household contacts may be affected with anthropophilic species like T. tonsurans. 2, 1, 8

Additional preventive measures:

• Clean all fomites (combs, brushes, towels) with disinfectant or 2% sodium hypochlorite solution 2, 1, 8
• Avoid skin-to-skin contact with infected individuals 2, 1
• Do not share towels or personal items 2, 1
• Cover lesions during treatment 2

Important Safety Considerations

Terbinafine contraindications:

• Active or chronic liver disease 1
• Lupus erythematosus 1
• Common side effects include gastrointestinal disturbances (49%) such as nausea, diarrhea, and taste disturbance 1
• Serious adverse events are rare (0.04% incidence) including Stevens-Johnson syndrome 1

Itraconazole precautions:

• Baseline liver function tests recommended, especially with pre-existing hepatic abnormalities 2
• Multiple significant drug interactions require careful medication review 2, 1

Common Pitfalls to Avoid

• Do NOT use combination antifungal-corticosteroid creams as first-line therapy - while they may show higher clinical cure rates at end of treatment, they carry risks of skin atrophy and other steroid-associated complications, and antifungal stewardship guidelines recommend against their routine use 5, 4
• Do NOT rely on clinical appearance alone without mycological confirmation 1, 5
• Do NOT stop treatment when lesions clear clinically - continue until mycological cure is documented 1, 3
• Do NOT use topical therapy alone for extensive disease - oral therapy is required 1