What is the appropriate oseltamivir (Tamiflu) dose for a 25‑lb (≈11 kg) child with normal renal function?

Oseltamivir Dosing for a 25‑lb Child

For a 25‑lb (≈11 kg) child with normal renal function, give 30 mg of oseltamivir twice daily for 5 days for treatment, or 30 mg once daily for 10 days for prophylaxis. 1, 2, 3

Weight‑Based Dosing Algorithm

A 25‑lb child weighs approximately 11 kg, which falls into the ≤15 kg weight category used by the American Academy of Pediatrics for children ≥12 months of age. 4, 1, 2

• Treatment dose: 30 mg orally twice daily for 5 days 4, 1, 2
• Prophylaxis dose: 30 mg orally once daily for 10 days 1, 2, 3

Practical Administration

• The 30 mg dose equals 5 mL of the oral suspension (6 mg/mL concentration when reconstituted). 4, 3
• Alternatively, one 30 mg capsule can be used if the child can swallow capsules. 4
• Administer with food to reduce nausea and vomiting, which occur in approximately 10% of pediatric patients. 1, 2, 3, 5

Critical Timing Considerations

• Initiate therapy within 48 hours of symptom onset for maximal benefit; starting within 12–24 hours provides substantially greater effectiveness (reduces illness duration by an additional 74.6 hours when started within 12 hours versus 48 hours). 2, 5
• Early treatment reduces illness duration by approximately 1–1.5 days (26–36% reduction) and decreases secondary complications such as acute otitis media by 44%. 2, 3

Common Pitfalls to Avoid

• Do NOT use mg/kg dosing (3 mg/kg or 3.5 mg/kg) for this child—those doses are reserved exclusively for infants <12 months of age. 1, 2
• Do NOT confuse treatment dosing (twice daily) with prophylaxis dosing (once daily). 1, 2
• Do NOT stop therapy early even if symptoms improve before day 5; complete the full 5‑day course. 2
• Do NOT delay treatment while awaiting laboratory confirmation during influenza season; clinical judgment is sufficient. 2

Age Verification

• This weight‑based categorical dosing (30 mg for ≤15 kg) applies only to children ≥12 months of age. 1, 2, 3
• If this child is <12 months old, you must instead use age‑ and weight‑specific mg/kg dosing (3 mg/kg for 0–8 months or 3.5 mg/kg for 9–11 months). 1, 2, 6
• If the child was born preterm, postmenstrual age‑based dosing is required (1.0–3.0 mg/kg depending on postmenstrual age) to prevent toxic accumulation. 4, 1, 2

Renal Function Consideration

• No dose adjustment is needed for normal renal function. 3
• If creatinine clearance is 10–30 mL/min, reduce to 30 mg once daily (instead of twice daily) for treatment. 4, 1, 2