From the Guidelines
For the treatment of toenail onychomycosis, the standard dose of Lamisil (terbinafine) is 250 mg taken once daily by mouth for 12–16 weeks. This extended treatment duration is necessary because the medication needs time to reach effective concentrations in the nail bed and nail plate, where the fungal infection resides. Terbinafine works by inhibiting the enzyme squalene epoxidase, which disrupts fungal cell membrane synthesis, ultimately killing the fungus. Complete cure rates may take several months to become apparent, as the infected nail needs to grow out completely. Patients should take the medication with or without food and should continue for the full prescribed duration even if improvement is seen earlier. Common side effects include headache, gastrointestinal disturbances, and rash. Liver function tests are typically recommended before starting therapy, as rare cases of hepatotoxicity have been reported 1. Patients should avoid alcohol during treatment and inform their healthcare provider of all other medications they are taking to prevent potential drug interactions.
Key Considerations
- The treatment duration for toenail onychomycosis is longer than for fingernail onychomycosis, typically 12–16 weeks for terbinafine 1.
- Terbinafine is generally preferred over itraconazole due to its higher efficacy and tolerability 1.
- Patients should be re-evaluated 3–6 months after treatment initiation and further treatment should be given if the disease persists 1.
- Common side effects of terbinafine include headache, gastrointestinal disturbances, and rash, and liver function tests are recommended before starting therapy 1.
Treatment Outcomes
- Complete cure rates of 70–80% can be expected for toenail infection 1.
- In cases of treatment failure, the reasons for such failure should be carefully considered, and either an alternative drug or nail removal in combination with a further course of therapy to cover the period of regrowth should be considered 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Fingernail onychomycosis: One 250 mg tablet, once daily for 6 weeks. Toenail onychomycosis: One 250 mg tablet, once daily for 12 weeks
The dose of lamisil (terbinafine) for the treatment of toenail onychomycosis is one 250 mg tablet, once daily for 12 weeks 2.
From the Research
Dose of Lamisil for Toenail Onychomycosis
- The recommended dose of Lamisil (terbinafine) for the treatment of toenail onychomycosis is 250 mg/day 3, 4.
- This dose is typically administered for 12 weeks 3, 4 or 16 weeks 3.
- Some studies have also investigated the use of pulsed dosing regimens, such as 500 mg/day for 1 week per month for 3 months 5 or 500 mg/day for 1 week every 4 weeks over 16 weeks 6.
- However, the efficacy of these pulsed regimens compared to continuous dosing is still a topic of debate, with some studies suggesting that continuous dosing may be more effective 5 while others find that pulsed dosing is at least as effective 6.
Efficacy of Different Dosing Regimens
- A study comparing 6 weeks of terbinafine treatment to 12 weeks found that the longer treatment duration was more effective in achieving mycological and clinical cure 7.
- Another study comparing continuous dosing to pulsed dosing found that continuous dosing was more effective in achieving mycological, clinical, and complete cure 5.
- In contrast, a retrospective analysis of patients treated with either continuous or pulsed dosing regimens found that the pulsed regimen was at least as effective as continuous dosing 6.