Oral Terbinafine for Tinea Corporis
Oral terbinafine is reserved for extensive tinea corporis, treatment failures, immunocompromised patients, or when hair follicles are involved—topical antifungals remain first-line for localized disease. 1
When to Use Oral Terbinafine
Oral antifungal therapy should be considered in specific clinical scenarios rather than as routine treatment:
- Extensive disease covering large body surface areas where topical therapy is impractical 1, 2
- Failed topical treatment after appropriate duration and adherence 1
- Immunocompromised patients (HIV, diabetes, transplant recipients) who have more severe and extensive infections 3
- Hair follicle involvement (tinea corporis with folliculitis), as topical agents cannot adequately penetrate follicles 4, 2
Dosing Regimen
When oral terbinafine is indicated for tinea corporis:
- Adults: 250 mg once daily for 1-2 weeks 1, 5
- Children 20-40 kg: 125 mg once daily for 2-4 weeks 4
- Children <20 kg: 62.5 mg once daily for 2-4 weeks 4
The shorter treatment duration compared to griseofulvin improves compliance 4.
Efficacy Evidence
Oral terbinafine demonstrates superior efficacy compared to older agents:
- 87.1% mycological cure at 6 weeks follow-up versus 54.8% with griseofulvin, with significantly lower relapse rates 6
- Particularly effective against Trichophyton rubrum and T. mentagrophytes, the most common causative organisms 7, 5
- Achieves mycological cure in >80% of patients with tinea corporis/cruris 5
Important caveat: Recent data from India shows concerning treatment failures, with only 20-33% overall cure rates after 4 weeks of treatment, and doubling the dose to 500 mg daily provided no additional benefit 8. This likely reflects emerging resistant strains in certain geographic regions.
Safety Profile
Terbinafine is generally well tolerated with predictable side effects:
- Gastrointestinal disturbances (49%): nausea, diarrhea, taste disturbance 7
- Dermatological reactions (23%): rash, pruritus, urticaria 7, 4
- Serious adverse events are rare (0.04% incidence), including Stevens-Johnson syndrome and toxic epidermal necrolysis 7
- Taste disturbance can rarely be permanent—patients must be warned 7
Contraindications
Drug Interactions
Terbinafine has minimal drug-drug interactions compared to azoles, making it preferable in immunocompromised patients on multiple medications 3. The only significant interaction involves drugs metabolized by cytochrome P450 2D6 7.
Treatment Monitoring
Mycological cure, not just clinical improvement, is the definitive endpoint 1, 4:
- Confirm dermatophyte infection via KOH preparation or culture before initiating therapy 1
- Follow-up with repeat mycology sampling until clearance is documented 1
- If clinical improvement occurs but mycology remains positive, continue therapy for an additional 2-4 weeks 1
Critical Clinical Pitfalls
Avoid combination antifungal-corticosteroid products, as they worsen outcomes and may contribute to resistance 2. This represents a major stewardship concern.
Screen and treat household contacts, as >50% may be affected with anthropophilic species like T. tonsurans 1. Clean all fomites (combs, brushes, towels) with disinfectant or 2% sodium hypochlorite solution 1.
First-Line Approach
Topical allylamines (terbinafine or naftifine) for 1-2 weeks remain first-line for localized tinea corporis 1. Reserve oral terbinafine for the specific indications outlined above, as it exposes patients to systemic side effects and potential drug costs without added benefit in simple, localized disease.