Terbinafine Regimen for Tinea Cruris
For tinea cruris, use topical terbinafine 1% cream applied once daily for 1 week as first-line therapy for limited disease, achieving mycological cure rates of approximately 94%; reserve oral terbinafine 250 mg once daily for 2-4 weeks for severe or extensive cases. 1, 2, 3
Topical Terbinafine (First-Line for Limited Disease)
- Terbinafine 1% cream applied once daily for 1 week is highly effective, with mycological cure rates of ~94% and is approved for patients 12 years and older 2, 3
- This short 7-day regimen maintains sustained high cure rates (84.2% vs 23.3% placebo) even 7 weeks after treatment cessation, reflecting terbinafine's fungicidal mechanism and residual tissue effect 3, 4
- Topical therapy is appropriate for limited disease without hair follicle involvement 1
Oral Terbinafine (For Severe or Extensive Disease)
Adult Dosing (>40 kg)
- Oral terbinafine 250 mg once daily for 2-4 weeks is the standard regimen for severe tinea cruris 5, 4
- The endpoint should be mycological cure (negative microscopy and culture), not just clinical improvement 1, 5
- If clinical improvement occurs but mycology remains positive, continue therapy for an additional 2-4 weeks 5
Pediatric Dosing
- Children 20-40 kg: 125 mg once daily for 2-4 weeks 1
- Children <20 kg: 62.5 mg once daily for 2-4 weeks 1
Important Clinical Considerations
Treatment Efficacy Concerns
- Recent evidence shows concerning resistance patterns: A 2023 study demonstrated only 25.9% overall cure rates with oral terbinafine 250 mg after 4 weeks, and doubling the dose to 500 mg provided no additional benefit (33.3% cure rate, P=0.82) 6
- A 2019 study found itraconazole superior to terbinafine for tinea cruris/corporis, with 91.8% vs 74.3% mycological cure rates respectively 7
- Given emerging resistance, consider itraconazole 100 mg daily for 2 weeks or 200 mg daily for 1 week as an alternative first-line oral agent for severe cases 2, 7
Contraindications
- Terbinafine is contraindicated in patients with active or chronic liver disease, lupus erythematosus, porphyria, or known hypersensitivity 1, 5
Common Pitfalls
- Do not rely solely on clinical appearance to determine treatment success—mycological cure must be confirmed, as clinical improvement may occur while infection persists 1, 5
- Treatment failure may result from poor compliance, suboptimal drug absorption, or organism insensitivity 1
- Common side effects include gastrointestinal disturbances and dermatological reactions 1
Prevention of Recurrence
- Complete drying of the crural folds after bathing is essential to prevent recurrence 1, 2
- Use separate clean towels for drying the groin versus other body parts 2
- Cover active foot lesions with socks before wearing undershorts to reduce direct contamination 2
- Address predisposing factors such as obesity and diabetes 2
- Avoid sharing towels and personal items that could serve as fomites 5, 2