Terbinafine 250mg Daily Dosing: Total Number of Doses Over 12 Weeks
For a standard 12-week treatment course of toenail onychomycosis, you take terbinafine 250 mg once daily for a total of 84 doses (12 weeks × 7 days/week = 84 tablets). 1, 2
Standard Dosing Regimen
One tablet (250 mg) is taken once daily, every single day, for the entire 12-week duration without interruption. 1, 3, 2 This is continuous daily therapy, not pulse therapy—there are no "off" weeks or breaks in treatment. 4
Duration by Indication
- Toenail onychomycosis: 250 mg once daily for 12 weeks (84 total doses) 1, 3, 2
- Severe toenail infections: May extend to 16 weeks (112 total doses) 1, 3
- Fingernail onychomycosis: 250 mg once daily for 6 weeks (42 total doses) 1, 3, 2
Critical Prescribing Details
Continuous daily dosing is superior to intermittent or pulse regimens for terbinafine. 3, 4 A large randomized trial demonstrated that intermittent terbinafine (350 mg daily for 2 weeks on/2 weeks off) was significantly less effective than standard continuous dosing, with complete cure rates approximately 6% lower. 4 Unlike itraconazole, which can be given as pulse therapy, terbinafine must be taken every day without breaks to achieve optimal outcomes. 3, 4
Missed Dose Instructions
If a dose is forgotten, take it as soon as remembered unless less than 4 hours remain before the next scheduled dose—in that case, skip the missed dose. 2 Never double up doses. 2
Why 12 Weeks Is Sufficient
Terbinafine persists in the nail for up to 30 weeks (approximately 6 months) after treatment completion due to its long half-life and lipophilic properties, allowing continued fungicidal activity even after stopping therapy. 1, 3, 5 This pharmacokinetic property is why:
- You don't need to treat until the nail grows out completely 1, 2
- Mycological and clinical cure rates continue to improve for months after stopping treatment 5, 6
- A 12-week course is sufficient for most toenail infections 6
Pre-Treatment Requirements
Baseline liver function tests (ALT and AST) and complete blood count must be obtained before starting terbinafine. 1, 3, 7, 2 This is mandatory for all patients. 2
Enhanced Monitoring Needed For:
- History of hepatitis or liver disease 1, 7
- Heavy alcohol consumption 1, 7
- Concurrent hepatotoxic medications 7
- Pre-existing abnormal liver enzymes 3, 7
Common Pitfall to Avoid
Do not confuse terbinafine dosing with itraconazole pulse therapy. 3 Itraconazole can be given as 400 mg daily for 1 week per month (pulse dosing), but terbinafine requires continuous daily administration. 3, 4 Attempting to use terbinafine intermittently significantly reduces efficacy. 4
Expected Timeline for Results
The optimal clinical effect appears several months after completing treatment and achieving mycological cure, due to the time required for healthy nail outgrowth. 2 Patients should be followed for at least 48 weeks from treatment initiation to assess response and detect potential relapse. 3