Oseltamivir (Tamiflu) Dosage
Oseltamivir dose depends on the indication — different for flu treatment and prophylaxis. Dose adjustment is required in renal impairment.
Adult Treatment Dose (Flu Treatment)
Dose: 75mg twice daily (BD)
Duration: 5 days — do not stop even if you feel better
CRITICAL: Start within 48 hours of symptom onset — benefit is minimal if started later in healthy adults
Starting Rule: The sooner you start, the better — within the first 12 hours is ideal
Adult Prophylaxis Dose (Prevention)
Post-exposure prophylaxis: 75mg once daily (OD) for 10 days
Outbreak prophylaxis: 75mg once daily — up to 6 weeks (specialist guidance)
Child Dose
| Weight | Treatment Dose (BD x 5 days) | Prophylaxis Dose (OD x 10 days) |
|---|---|---|
| <15 kg | 30mg BD | 30mg OD |
| 15-23 kg | 45mg BD | 45mg OD |
| 24-40 kg | 60mg BD | 60mg OD |
| >40 kg | 75mg BD (adult dose) | 75mg OD |
Always confirm the exact child dose with a paediatrician — especially in children under 1 year.
Renal Impairment Dose Adjustment
| CrCl (mL/min) | Treatment Dose | Prophylaxis Dose |
|---|---|---|
| >60 | 75mg BD x 5 days | 75mg OD x 10 days |
| 30-60 | 30mg BD x 5 days | 30mg OD x 10 days |
| 10-30 | 30mg OD x 5 days | 30mg alternate days |
| <10 / dialysis | Specialist guidance | Specialist guidance |
Dose adjustment is ESSENTIAL in renal impairment — confirm with a nephrologist or internist.
How to Take
- Take the capsule with food
- Complete the full 5-day course (to prevent antiviral resistance)
- At the same time each day
- Swallow the whole capsule with water
Missed Dose
If you miss a dose, take it as soon as remembered. If the next dose is close, skip it. Never take a double dose. Complete the full 5-day course — preventing antiviral resistance is essential.
Overdose
Nausea, vomiting, and dizziness may occur. It is generally self-limiting but contact a doctor immediately.
Dose Summary Table
| Indication | Patient | Dose | Duration |
|---|---|---|---|
| Treatment | Adult (>40kg) | 75mg BD | 5 days |
| Treatment | Child <15kg | 30mg BD | 5 days |
| Treatment | Child 15-23kg | 45mg BD | 5 days |
| Prophylaxis | Adult | 75mg OD | 10 days |
| Prophylaxis | Child <15kg | 30mg OD | 10 days |
The information in this guide is for educational purposes only. Always confirm the dose with your doctor or pharmacist — especially in renal impairment.