Oseltamivir Weight-Based Dosing
For children ≥1 year, oseltamivir dosing is weight-based: 30 mg twice daily for ≤15 kg, 45 mg twice daily for >15-23 kg, 60 mg twice daily for >23-40 kg, and 75 mg twice daily for >40 kg, while adults and adolescents ≥13 years receive a standard 75 mg twice daily for 5 days. 1, 2, 3
Adult and Adolescent Dosing (≥13 years)
- Standard dose: 75 mg orally twice daily for 5 days for treatment of influenza 1, 2, 3
- For prophylaxis: 75 mg once daily for 10 days (post-exposure) or up to 6 weeks (seasonal prophylaxis) 2, 3
- Administration with food may improve gastrointestinal tolerability 1, 4
Pediatric Weight-Based Dosing (≥1 year)
Treatment dosing (twice daily for 5 days): 1, 2, 3
- ≤15 kg (≤33 lb): 30 mg twice daily = 5 mL of oral suspension
- >15-23 kg (>33-51 lb): 45 mg twice daily = 7.5 mL of oral suspension
- >23-40 kg (>51-88 lb): 60 mg twice daily = 10 mL of oral suspension
- >40 kg (>88 lb): 75 mg twice daily = 12.5 mL of oral suspension
Prophylaxis dosing: Same weight-based doses but once daily instead of twice daily for 10 days 2, 3
Infant Dosing (<1 year)
- Infants 9-11 months: 3.5 mg/kg per dose twice daily for 5 days 1, 2
- Term infants 0-8 months: 3 mg/kg per dose twice daily for 5 days 1, 2, 3
- Infants ≥2 weeks: 3 mg/kg twice daily for treatment 3
Preterm Infant Dosing (Based on Postmenstrual Age)
Critical consideration: Preterm infants require significantly lower doses due to immature renal function and risk of drug accumulation 1, 4
- <38 weeks postmenstrual age: 1.0 mg/kg twice daily 1, 2
- 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily 1, 2
- >40 weeks postmenstrual age: 3.0 mg/kg twice daily 1, 2
Renal Impairment Adjustments
For creatinine clearance 10-30 mL/min: 1, 2, 3
- Treatment: 30 mg once daily for 5 days (reduced from twice daily)
- Prophylaxis: 30 mg once daily OR 75 mg every other day for 10 days
For creatinine clearance >30-60 mL/min: 3
- Treatment: 30 mg twice daily for 5 days
- Prophylaxis: 30 mg once daily
Formulation and Administration
- Available as capsules: 30 mg, 45 mg, 75 mg 1, 3
- Oral suspension: 6 mg/mL when reconstituted 1, 3
- Capsules can be opened and mixed with liquid if patient cannot swallow whole 4
- Take with food to reduce nausea and vomiting, which occur in approximately 10% of patients 1, 4, 5
Critical Timing Considerations
- Initiate treatment within 48 hours of symptom onset for maximum effectiveness 4, 3
- Treatment within 12 hours reduces illness duration by an additional 74.6 hours compared to starting at 48 hours 5
- Treatment within 24 hours reduces illness duration by an additional 53.9 hours compared to starting at 48 hours 5