Treatment of Ringworm (Tinea Corporis and Tinea Cruris)
For uncomplicated ringworm of the body or groin, apply topical terbinafine once daily for 1 week, which provides superior efficacy compared to placebo and requires the shortest treatment duration among available options.
First-Line Topical Treatment
Topical terbinafine is the preferred initial therapy for ringworm, demonstrating significantly higher clinical cure rates compared to placebo (RR 4.51,95% CI 3.10 to 6.56, NNT 3) 1. According to FDA labeling, terbinafine cream should be applied once daily (morning or night) for 1 week for both jock itch and ringworm 2. This represents the shortest effective treatment duration among topical antifungals.
Application Instructions
- Wash the affected skin with soap and water and dry completely before applying 2
- Apply the medication to the affected area and approximately 1 inch beyond the visible border of the rash 2
- Wash hands after each use 2
Alternative Topical Agents
If terbinafine is unavailable or not tolerated, naftifine 1% cream applied once or twice daily is an effective alternative, showing mycological cure rates significantly better than placebo (RR 2.38,95% CI 1.80 to 3.14, NNT 3) 1. Treatment duration is typically 1-2 weeks.
Clotrimazole 1% cream applied twice daily for 2-4 weeks is another reasonable option, with mycological cure rates favoring it over placebo (RR 2.87,95% CI 2.28 to 3.62, NNT 2) 1. Other azole antifungals (miconazole, econazole, ketoconazole) have similar efficacy when applied twice daily for 2-4 weeks 3, 1.
When to Use Oral Antifungal Therapy
Oral antifungal agents are indicated for patients with:
- Extensive disease involving large body surface areas 4
- Lack of response to topical treatment after 2-4 weeks 4
- Immunocompromise 4
- Hair follicle involvement (tinea capitis requires oral therapy) 4, 5
Oral terbinafine is considered first-line systemic therapy because it is well tolerated, effective, and inexpensive 4. Alternative oral agents include griseofulvin, itraconazole, and fluconazole, though these may require longer treatment courses 3, 4.
Important Clinical Pitfalls
Avoid combination antifungal-corticosteroid creams as initial therapy. While these combinations show higher clinical cure rates at the end of treatment (RR 0.67 for azoles alone vs. azole-steroid combinations), they provide no difference in mycological cure rates (RR 0.99,95% CI 0.93 to 1.05) 1. The use of combination products is not recommended in clinical guidelines and may contribute to antifungal resistance 4.
Clinical diagnosis without confirmatory testing may be unreliable, as other conditions can mimic ringworm, including eczema, psoriasis, and contact dermatitis 4. Consider obtaining skin scrapings for KOH preparation or fungal culture when the diagnosis is uncertain 3, 6.
Emerging resistant tinea infections may not respond to first-line topical or oral antifungals and may require prolonged oral antifungal therapy and specialized diagnostic testing 4. If a patient fails to respond to appropriate first-line therapy, consider referral to dermatology.
Treatment Duration and Follow-Up
- Topical terbinafine: 1 week for tinea corporis and tinea cruris 2
- Topical azoles: 2-4 weeks, applied twice daily 1
- Topical naftifine: 1-2 weeks 1
Good personal hygiene is an important adjunct to antifungal therapy 3. For tinea cruris, patients should wear well-fitting, ventilated clothing and keep the groin area clean and dry 2.