How Often Can Tamiflu Be Repeated?
Tamiflu (oseltamivir) is given as a standard 5-day treatment course at 75 mg twice daily for adults, and this course is not routinely repeated for the same influenza illness episode. 1
Standard Treatment Duration and Dosing
Adults and adolescents ≥13 years: 75 mg twice daily for 5 days 1
Pediatric weight-based dosing for treatment (all given twice daily for 5 days): 1
- ≤15 kg: 30 mg twice daily
15-23 kg: 45 mg twice daily
23-40 kg: 60 mg twice daily
40 kg: 75 mg twice daily
The 5-day treatment course should be completed in full, even if symptoms improve earlier 2
When Treatment Duration May Be Extended Beyond 5 Days
Immunocompromised patients may require extended treatment duration beyond the standard 5 days due to prolonged viral shedding, though specific duration should be guided by clinical judgment and ongoing viral replication 1, 3
- Transplant recipients and severely immunosuppressed patients have demonstrated prolonged viral shedding (up to 14 days or more) 1
- Extended prophylaxis up to 12 weeks may be considered in select immunocompromised patients during institutional outbreaks 3
Prophylaxis Dosing (Different from Treatment)
Post-exposure prophylaxis uses a different regimen than treatment: 1
- Adults: 75 mg once daily (not twice daily) for 10 days after household exposure 1
- Institutional outbreak control: Continue for ≥2 weeks or until 1 week after outbreak ends 3
- Prophylaxis is not a repeated treatment course—it's a distinct indication with once-daily dosing 1
Critical Renal Dosing Adjustments
For patients with creatinine clearance 10-30 mL/min: 1, 2
- Treatment: 75 mg once daily (not twice daily) for 5 days
- Prophylaxis: 30 mg once daily OR 75 mg every other day for 10 days
This is a dose reduction, not a course repetition 1
Important Clinical Caveats
There is no evidence supporting repeating a 5-day treatment course for the same influenza episode 4
If symptoms persist or worsen after completing oseltamivir, consider: 1, 2
- Antiviral resistance (test for H275Y mutation if available)
- Secondary bacterial superinfection (S. pneumoniae, S. aureus, H. influenzae)
- Alternative diagnosis
Double-dose oseltamivir (150 mg twice daily) has been suggested by some experts for critically ill patients, but randomized trials found no significant survival benefit with this approach 1, 4
The standard 5-day course provides an 82% reduction in odds of in-patient mortality when compared to no treatment 5
Common Pitfall to Avoid
Do not confuse treatment dosing (twice daily for 5 days) with prophylaxis dosing (once daily for 10+ days)—these are distinct clinical scenarios with different regimens, not repeated courses of the same treatment 1, 3