Oral Terbinafine Dosing for Fungal Infections
The standard recommended dose of oral terbinafine for fungal infections is 250 mg daily for adults, with treatment duration of 6 weeks for fingernail infections and 12 weeks for toenail infections. 1, 2
Adult Dosing
- Terbinafine 250 mg daily is the standard adult dose for dermatophyte infections 1, 2
- Treatment duration varies by infection site:
- Patients should be re-evaluated 3-6 months after treatment initiation to assess response 2
Pediatric Dosing
Terbinafine dosing for children is weight-based 1:
- < 20 kg: 62.5 mg daily 1
- 20-40 kg: 125 mg daily 1
40 kg: 250 mg (adult dose) daily 1
- Duration: 6 weeks for fingernail infections and 12 weeks for toenail infections 1
Special Populations
Diabetic Patients
- Terbinafine is the oral antifungal of choice for diabetic patients with onychomycosis 1
- Standard adult dosing applies (250 mg daily) 1
- Preferred over itraconazole due to lower risk of drug interactions and no contraindication in cardiac disease 1
Immunosuppressed Patients
- Terbinafine is preferred over itraconazole and ketoconazole in immunosuppressed patients (including HIV) due to lower risk of interactions with antiretrovirals 1
- Standard adult dosing applies (250 mg daily) 1
Monitoring and Safety Considerations
- Baseline liver function tests are recommended before starting treatment 2, 3
- More vigilant monitoring is advised in patients with 2:
- Pre-existing liver disease
- Concomitant hepatotoxic medications
- Continuous therapy for more than one month
- History of heavy alcohol consumption
Contraindications
- Active or chronic liver disease 1, 2
- History of allergic reaction to oral terbinafine 3
- Lupus erythematosus 2, 3
Clinical Efficacy
- Terbinafine has demonstrated superior efficacy compared to other antifungals for dermatophyte infections 4
- Mycological cure rates of >80% have been reported in clinical trials 5
- A randomized study showed that 12 weeks of treatment was optimal for toenail onychomycosis, with 71% cure rate at 48 weeks follow-up 6
Common Side Effects
- Gastrointestinal symptoms (most common): nausea, diarrhea, dyspepsia 3, 7
- Taste disturbance (usually improves after stopping treatment) 3
- Rash and pruritus 3, 7
- Headache 3
Drug Interactions
- Terbinafine has minimal drug interactions compared to azole antifungals 1, 2
- Main interaction concern is with drugs metabolized by cytochrome P450 2D6 isoenzyme 1, 2
Important Clinical Pearls
- Terbinafine is fungicidal against dermatophytes with very low minimum inhibitory concentrations (approximately 0.004 μg/mL) 2
- It can be taken with or without food 3
- Nail terbinafine concentrations are detected within 1 week after starting therapy and persist for at least 30 weeks after completing treatment 4
- For Candida infections, itraconazole is generally preferred over terbinafine due to better efficacy 1