Pediatric Tamiflu (Oseltamivir) Dosing
For pediatric patients ≥12 months, use weight-based dosing: ≤15 kg receive 30 mg twice daily, >15-23 kg receive 45 mg twice daily, >23-40 kg receive 60 mg twice daily, and >40 kg receive 75 mg twice daily for 5 days. 1, 2, 3
Treatment Dosing by Age Group
Infants <12 Months
- 9-11 months: 3.5 mg/kg per dose twice daily for 5 days 1, 2, 4
- Term infants 0-8 months: 3 mg/kg per dose twice daily for 5 days 1, 2, 4
- The 3 mg/kg dose produces target drug exposures in infants 0-8 months, though variability is greater in infants <3 months 4
Preterm Infants (Postmenstrual Age-Based)
Preterm infants require substantially lower doses due to immature renal function: 1, 2
- <38 weeks postmenstrual age: 1.0 mg/kg twice daily for 5 days 1, 2
- 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily for 5 days 1, 2
- >40 weeks postmenstrual age: 3.0 mg/kg twice daily for 5 days 1, 2
Children ≥12 Months (Weight-Based)
Standard weight-based dosing for 5 days, twice daily: 1, 2, 3
- ≤15 kg (≤33 lb): 30 mg twice daily = 5 mL oral suspension 1, 3
- >15-23 kg (>33-51 lb): 45 mg twice daily = 7.5 mL oral suspension 1, 3
- >23-40 kg (>51-88 lb): 60 mg twice daily = 10 mL oral suspension 1, 3
- >40 kg (>88 lb): 75 mg twice daily = 12.5 mL oral suspension 1, 3
Adolescents ≥13 Years
Prophylaxis Dosing
Post-Exposure Prophylaxis (10 days, once daily)
Initiate within 48 hours of exposure to infected individual: 1, 5
- Infants 3-11 months: 3 mg/kg once daily for 10 days 1, 2
- Prophylaxis NOT recommended for infants <3 months unless situation is judged critical due to limited safety data 1
- Children ≥12 months: Same weight-based doses as treatment, but once daily instead of twice daily for 10 days 1, 2
- Adolescents ≥13 years: 75 mg once daily for 10 days 2, 5
Renal Impairment Adjustments
For patients with creatinine clearance 10-30 mL/min: 1, 2
- Treatment: 75 mg once daily (instead of twice daily) for 5 days 1
- Prophylaxis: 30 mg once daily for 10 days OR 75 mg every other day for 10 days (5 total doses) 1, 2
Formulation and Administration
Available Formulations
- Capsules: 30 mg, 45 mg, 75 mg 1, 2, 3
- Oral suspension: 6 mg/mL when reconstituted (preferred for children who cannot swallow capsules) 1, 3
Administration Tips
Take with food to reduce gastrointestinal side effects (nausea and vomiting occur in 10-15% of patients but are mild and transient) 1, 6
Capsules can be opened and contents mixed with liquid if patient cannot swallow whole 5
Critical Timing Considerations
Treatment must be initiated within 48 hours of symptom onset for maximum effectiveness (reduces illness duration by 1-1.5 days), though should not be withheld in high-risk or hospitalized patients presenting beyond 48 hours 1, 2, 5
Prophylaxis should be initiated within 48 hours following close contact with confirmed or suspected influenza case 1, 5
Common Pitfalls to Avoid
Do not use fixed dosing in infants <12 months—always calculate mg/kg doses based on actual weight 1, 4
Do not forget postmenstrual age adjustments in preterm infants—using term infant doses can cause toxicity due to immature renal function 1, 2
Avoid live attenuated influenza vaccine (LAIV) within 48 hours before oseltamivir and do not use oseltamivir for 14 days after LAIV vaccination 1, 2