Pediatric Tamiflu (Oseltamivir) Dosing
Oseltamivir dosing in children is weight-based for those ≥12 months and age/weight-based for infants, with treatment initiated within 48 hours of symptom onset for 5 days at twice-daily dosing, and prophylaxis given 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) twice daily 1, 3
- >15-23 kg (>33-51 lb): 45 mg (7.5 mL) twice daily 1, 3
- >23-40 kg (>51-88 lb): 60 mg (10 mL) twice daily 1, 3
- >40 kg (>88 lb): 75 mg (12.5 mL) twice daily 1, 3
Infants <12 months (Age-Based)
- 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
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 1, 2
- 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily 1, 2
- >40 weeks postmenstrual age: 3.0 mg/kg twice daily 1, 2
Prophylaxis Dosing (10 days, once daily)
Children ≥12 months (Weight-Based)
Use the same weight-based doses as treatment, but once daily instead of twice daily for 10 days: 1, 2
- ≤15 kg: 30 mg (5 mL) once daily 1
- >15-23 kg: 45 mg (7.5 mL) once daily 1
- >23-40 kg: 60 mg (10 mL) once daily 1
- >40 kg: 75 mg (12.5 mL) once daily 1
Infants 3-11 months
- 3 mg/kg once daily for 10 days 1, 2
- Prophylaxis is NOT recommended for infants <3 months unless the situation is judged critical due to limited safety and efficacy data 1
Who Should Receive Treatment
Regardless of vaccination status, treat the following children as early as possible: 1
- All children hospitalized with suspected influenza 1
- Children with severe, complicated, or progressive illness attributable to influenza, regardless of symptom duration 1
- Children at high risk for complications (age <2 years, chronic medical conditions including asthma, cardiac disease, diabetes, immunodeficiency) 1
Consider treatment for: 1
- Any otherwise healthy child with suspected influenza, especially if treatment can start within 48 hours 1
- Children whose household contacts are <6 months old or have high-risk conditions 1
Critical Timing Considerations
Treatment provides maximum benefit when started within 48 hours of symptom onset, reducing illness duration by 1-1.5 days (26-36% reduction) and decreasing complications including acute otitis media by 34-44%. 1, 2, 4
However, treatment after 48 hours still provides substantial benefit in hospitalized children and those with moderate-to-severe or progressive disease, and should be strongly considered. 1
For prophylaxis, initiate within 48 hours following close contact with an infected individual. 2, 5
Renal Impairment Adjustments
For patients with creatinine clearance 10-30 mL/min: 1
- 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
Formulation and Administration
Oseltamivir is available as: 1, 3
If commercial suspension is unavailable, capsules can be opened and contents mixed with simple syrup or Ora-Sweet SF by retail pharmacies to achieve 6 mg/mL concentration. 1
Administration with food significantly reduces nausea and vomiting (occurring in ~10-15% of children), which are the most common adverse effects. 1, 5
Common Pitfalls to Avoid
- Do not withhold treatment while awaiting laboratory confirmation in high-risk patients, as rapid antigen tests have poor sensitivity 1, 2
- Do not refuse treatment after 48 hours in hospitalized or severely ill children—benefits persist even with delayed initiation 1
- Do not use adult dosing in children >40 kg who are <13 years old—use weight-based pediatric dosing 1
- Do not forget to adjust doses in preterm infants based on postmenstrual age, not just weight, to avoid toxicity 1, 2
- Do not use prophylaxis in infants <3 months unless the clinical situation is critical 1