What is the recommended dosage and treatment duration of Tamiflu (oseltamivir) for pediatric patients with influenza?

Tamiflu (Oseltamivir) Dosing in Pediatrics

For pediatric influenza treatment, administer oseltamivir twice daily for 5 days using weight-based dosing for children ≥12 months (30-75 mg based on weight) and age-based mg/kg dosing for infants <12 months, with treatment ideally initiated within 48 hours of symptom onset. 1, 2, 3

Treatment Dosing (5 Days, Twice Daily)

Children ≥12 Months (Weight-Based)

• ≤15 kg (≤33 lb): 30 mg twice daily 1, 2, 3
• >15-23 kg (33-51 lb): 45 mg twice daily 1, 2, 3
• >23-40 kg (51-88 lb): 60 mg twice daily 1, 2, 3
• >40 kg (>88 lb): 75 mg twice daily 1, 2, 3

Infants <12 Months (Age-Based, mg/kg Dosing)

• 9-11 months: 3.5 mg/kg per dose twice daily 1, 2
• Term infants 0-8 months: 3 mg/kg per dose twice daily 1, 2, 3
• Preterm infants require postmenstrual age-based dosing due to immature renal function: 1, 2
  • <38 weeks postmenstrual age: 1.0 mg/kg twice daily
  • 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily

  • 40 weeks postmenstrual age: 3.0 mg/kg twice daily

Adolescents ≥13 Years

• 75 mg twice daily for 5 days 1, 2, 3

Prophylaxis Dosing (10 Days, Once Daily)

Initiate within 48 hours of close contact with an infected individual. 2, 3

Children ≥12 Months (Weight-Based)

• ≤15 kg: 30 mg once daily 1, 2
• >15-23 kg: 45 mg once daily 1, 2
• >23-40 kg: 60 mg once daily 1, 2
• >40 kg: 75 mg once daily 1, 2

Infants 3-11 Months

• 3 mg/kg once daily for 10 days 2
• Prophylaxis NOT recommended for infants <3 months unless the situation is judged critical due to limited safety data 1, 2

Adolescents ≥13 Years

• 75 mg once daily for 10 days post-exposure or up to 6 weeks during community outbreak 2, 3

Formulation and Administration

Available Forms

• Capsules: 30 mg, 45 mg, 75 mg 1, 2, 3
• Oral suspension: 6 mg/mL when reconstituted (preferred for patients who cannot swallow capsules) 1, 2, 3

Suspension Dosing Volumes

• 30 mg dose = 5 mL 1, 2
• 45 mg dose = 7.5 mL 1, 2
• 60 mg dose = 10 mL 1, 2
• 75 mg dose = 12.5 mL 1, 2

Administration Tips

• Can be given with or without food, though administration with meals improves gastrointestinal tolerability and reduces nausea/vomiting 1, 2, 3
• If commercial suspension unavailable, pharmacies can compound suspension from capsules to achieve 6 mg/mL concentration 1, 2

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
• Prophylaxis: 30 mg once daily for 10 days OR 75 mg every other day for 10 days (5 total doses)

Critical Timing Considerations

Treatment should be initiated within 48 hours of symptom onset for maximum effectiveness, though later initiation can still provide benefit in hospitalized or high-risk patients. 2, 4, 3

For severe or complicated influenza (ICU admission, pneumonia, immunocompromised patients), consider extending treatment beyond 5 days to 7-10+ days based on clinical status and viral clearance. 4

Common Pitfalls to Avoid

• Do not automatically stop at 5 days in critically ill or immunocompromised patients who may have prolonged viral replication 4
• Do not withhold treatment in hospitalized patients simply because >48 hours have elapsed since symptom onset, as treatment can still reduce morbidity even when initiated late 4
• Do not use standard term infant dosing in preterm infants without adjusting for postmenstrual age, as this can lead to 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 2