Oral Antifungal Treatment for Ringworm (Dermatophytosis)
Primary Recommendation
For ringworm (dermatophytosis), oral terbinafine 250 mg daily is the treatment of choice, with treatment duration of 2-4 weeks depending on the site and severity of infection. 1, 2
Treatment Algorithm
First-Line Therapy: Terbinafine
Terbinafine 250 mg once daily is the most effective oral antifungal for dermatophyte infections (ringworm), demonstrating superior fungicidal activity with the lowest MIC (minimal inhibitory concentration) against dermatophytes compared to all other systemic antifungals 3, 1
Treatment duration varies by site:
Terbinafine achieves an MIC:MFC ratio of 1:1, meaning it is both fungistatic and fungicidal at the same concentration, allowing for shorter treatment courses 3
Therapeutic drug levels persist in tissues for weeks after treatment cessation, contributing to sustained efficacy 3, 1
Alternative Therapy: Itraconazole
Itraconazole can be used as an alternative, though it is less effective than terbinafine for dermatophyte infections 1
For onychomycosis specifically, itraconazole pulse therapy (200 mg twice daily for 1 week per month × 3 pulses) showed only 38-49% mycologic cure rates compared to 76-81% with terbinafine 1
Itraconazole has more drug interactions and erratic bioavailability compared to terbinafine 4
Third-Line Option: Fluconazole
Fluconazole is the least preferred option for dermatophyte ringworm, with limited evidence supporting its use 4
Fluconazole is more appropriate for Candida infections rather than dermatophytes 5
When used for dermatophyte onychomycosis, fluconazole requires 150 mg weekly for 9-18 months, making it impractical for most ringworm cases 4
Clinical Efficacy Data
In post-marketing surveillance of 454 patients with superficial fungal skin infections, terbinafine 250 mg daily for 2 weeks achieved good-to-excellent clinical efficacy in 97% of patients 2
After 4 weeks of terbinafine treatment, erythema was absent in 85% of patients, scaling in 82%, and pruritus in 94% 2
Long-term follow-up studies demonstrate terbinafine's superior durability, with mycologic relapse rates of only 23% at 5 years compared to 53% with itraconazole 1
Safety Profile
Terbinafine is generally well tolerated, with adverse events reported in only 5.3-10.5% of patients 3, 2
Most common side effects are gastrointestinal disturbances (nausea, abdominal pain, diarrhea) occurring in approximately 5% of patients, and minor skin rashes in 2% 3, 2
Critical advantage: Terbinafine has a low potential for drug-drug interactions, unlike azole antifungals (itraconazole, fluconazole) which have significant cytochrome P450 interactions 1
Important Clinical Pitfalls
Do not use fluconazole as first-line for dermatophyte ringworm - it is primarily indicated for Candida infections and has inferior efficacy against dermatophytes 5, 4
Avoid confusing ringworm (dermatophyte) with Candida infections - the provided guidelines 5, 6 focus on candidiasis treatment, which is a different fungal pathogen requiring different management
Ensure mycological confirmation when possible, as treatment selection and duration depend on the specific organism 1
For scalp ringworm (tinea capitis) in children, terbinafine 4-week courses are effective and well-tolerated 3