Tamiflu (Oseltamivir) Dosing for Children - Twice Daily Regimen
For children ≥12 months, use weight-based dosing twice daily for 5 days: ≤15 kg = 30 mg BID, >15-23 kg = 45 mg BID, >23-40 kg = 60 mg BID, and >40 kg = 75 mg BID. 1, 2
Weight-Based Dosing for Children ≥12 Months (Treatment)
The American Academy of Pediatrics provides clear weight-based dosing recommendations for treatment, administered twice daily for 5 days 1, 3:
- ≤15 kg (≤33 lb): 30 mg twice daily 1, 2
- >15-23 kg (>33-51 lb): 45 mg twice daily 1, 2
- >23-40 kg (>51-88 lb): 60 mg twice daily 1, 2
- >40 kg (>88 lb): 75 mg twice daily 1, 2
Dosing for Infants <12 Months
For term infants 0-8 months, use 3 mg/kg per dose twice daily for 5 days. 1, 2
For infants 9-11 months, use 3.5 mg/kg per dose twice daily for 5 days. 1, 4
The higher dose for 9-11 month olds is based on pharmacokinetic data showing that 3 mg/kg produces subtherapeutic drug exposures in this age group 4.
Preterm Infant Dosing (Based on Postmenstrual Age)
Preterm infants require lower doses due to immature renal function and risk of drug accumulation 1:
- <38 weeks postmenstrual age: 1.0 mg/kg twice daily 1
- 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily 1
- >40 weeks postmenstrual age: 3.0 mg/kg twice daily 1
For extremely preterm infants (<28 weeks), consult a pediatric infectious disease specialist 1.
Oral Suspension Volumes (6 mg/mL Concentration)
When using the oral suspension formulation 1, 2:
- 30 mg dose = 5 mL
- 45 mg dose = 7.5 mL
- 60 mg dose = 10 mL
- 75 mg dose = 12.5 mL
Renal Impairment Adjustments
For children with creatinine clearance 10-30 mL/min, reduce treatment dosing to 75 mg once daily (instead of twice daily) for 5 days. 1, 5
This adjustment is critical to prevent drug accumulation in patients with impaired renal function 1, 5.
Administration Considerations
Administer with food to improve gastrointestinal tolerability, as nausea and vomiting are the most common adverse effects 1, 2, 6. The medication can be given without regard to meals, but food reduces GI side effects 1, 2.
Initiate treatment within 48 hours of symptom onset for maximum benefit, though treatment should not be withheld in high-risk or hospitalized patients presenting beyond 48 hours 3, 7.
Duration of Treatment
The standard treatment duration is 5 days for all pediatric age groups. 1, 2 Immunocompromised patients may require extended treatment beyond 5 days if illness is prolonged 3.
Common Pitfalls to Avoid
Do not use the 30 mg unit dose for all 12-23 month olds: Research shows that 6 of 10 children in this age group receiving 30 mg had subtherapeutic drug levels 4. Weight-based dosing is more accurate.
Do not underdose infants 9-11 months: This age group requires 3.5 mg/kg (not 3 mg/kg) to achieve adequate drug exposure 1, 4.
Do not use term infant dosing for preterm infants: Preterm infants have immature renal function and require postmenstrual age-based dosing to avoid toxicity 1.
Do not delay treatment waiting for laboratory confirmation in high-risk patients, as rapid antigen tests have poor sensitivity 1, 3.