What is the dosing of Tamiflu (oseltamivir) for pediatric patients?

Pediatric Tamiflu (Oseltamivir) Dosing

For pediatric patients, oseltamivir dosing is weight-based for children ≥12 months and age/weight-based for infants <12 months, with treatment given twice daily for 5 days and prophylaxis once daily for 10 days. 1, 2

Treatment Dosing (5 days, twice daily)

Children ≥12 months to 12 years (Weight-Based)

• ≤15 kg (≤33 lb): 30 mg (5 mL of 6 mg/mL suspension) twice daily 1, 2
• >15-23 kg (>33-51 lb): 45 mg (7.5 mL) twice daily 1, 2
• >23-40 kg (>51-88 lb): 60 mg (10 mL) twice daily 1, 2
• >40 kg (>88 lb): 75 mg (12.5 mL) twice daily 1, 2

Infants <12 months (Age-Based)

• 9-11 months: 3.5 mg/kg per dose twice daily 1, 3
• Term infants 0-8 months: 3.0 mg/kg per dose twice daily 1, 2

Critical caveat: The FDA-approved dose is 3.0 mg/kg twice daily for all infants <12 months 2, but the most recent AAP guidelines (2024) recommend 3.5 mg/kg for 9-11 month-olds based on pharmacokinetic data showing improved drug exposure at this higher dose 1, 4.

Preterm Infants (Postmenstrual Age-Based)

Preterm infants require lower doses due to immature renal function 1, 3:

• <38 weeks postmenstrual age: 1.0 mg/kg twice daily 1, 3
• 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily 1, 3
• >40 weeks postmenstrual age: 3.0 mg/kg twice daily 1, 3

Prophylaxis Dosing (10 days, once daily)

Children ≥12 months (Weight-Based, Once Daily)

Use the same weight-based doses as treatment but once daily instead of twice daily 1, 2:

• ≤15 kg: 30 mg once daily 1
• >15-23 kg: 45 mg once daily 1
• >23-40 kg: 60 mg once daily 1
• >40 kg: 75 mg once daily 1

Infants 3-11 months

• 3.0 mg/kg once daily for 10 days 1

Infants <3 months

• Prophylaxis NOT recommended unless situation is judged critical, due to limited safety data 1, 3

Adolescents ≥13 years

• Treatment: 75 mg twice daily for 5 days 1, 2
• Prophylaxis: 75 mg once daily for 10 days 1, 2

Formulation and Administration

Available Forms

• Oral suspension: 6 mg/mL concentration (preferred for children who cannot swallow capsules) 1, 2
• Capsules: 30 mg, 45 mg, 75 mg 1, 2

Administration Tips

• Can be given with or without food, but taking with food may reduce nausea and vomiting 1, 2
• If commercial suspension unavailable: Capsules can be opened and mixed with sweetened liquid, or pharmacies can compound a 6 mg/mL suspension 1
• For infants <1 year: Use an appropriate measuring device (3 mL or 5 mL oral syringe) instead of the supplied syringe 1

Renal Impairment Adjustments

For patients with creatinine clearance 10-30 mL/min 1, 3:

• Treatment: 75 mg once daily (instead of twice daily) for 5 days 1, 3
• Prophylaxis: 30 mg once daily OR 75 mg every other day for 10 days 1, 3

Important: Renal dosing guidance in the FDA label is limited for pediatric patients; CDC dosing tables may be helpful for children >40 kg 1

Critical Timing Considerations

• Treatment should be initiated within 48 hours of symptom onset for maximum effectiveness 1, 2
• Prophylaxis should be initiated within 48 hours following close contact with an infected individual 1, 5, 2
• Duration: Treatment is 5 days; post-exposure prophylaxis is 10 days; community outbreak prophylaxis can extend up to 6 weeks 1, 2

Common Pitfalls to Avoid

• Do not confuse treatment dosing (twice daily) with prophylaxis dosing (once daily) - this is a frequent prescribing error 5
• Verify current weight to avoid dosing errors, especially in rapidly growing children 6
• Do not use adult dosing in children <40 kg - pharmacokinetic studies show children eliminate the drug faster and require weight-based dosing 4, 7
• Remember preterm infants need lower doses based on postmenstrual age, not just weight 1, 3