Oseltamivir Dosing for a 2-Year-Old Weighing 16.69 kg with Influenza B
For a 2-year-old child weighing 16.69 kg with influenza B, administer 45 mg (7.5 mL of the 6 mg/mL suspension) orally twice daily for 5 days. 1, 2, 3
Weight-Based Dosing Algorithm
Your patient falls into the >15 kg to ≤23 kg weight category, which requires the 45 mg dose—not the 30 mg dose used for children ≤15 kg. 1, 2, 3
- Children weighing >15 kg to 23 kg receive 45 mg twice daily for treatment (5 days). 1, 2, 3
- This translates to 7.5 mL of the 6 mg/mL oral suspension per dose. 1, 3
- Administer twice daily (approximately every 12 hours) for a total of 5 days. 1, 3
Practical Administration Instructions
- Measure precisely: Use a calibrated oral dosing syringe or device that accurately measures 7.5 mL—do not use household spoons. 1, 3
- Give with food: Administer oseltamivir with meals to reduce gastrointestinal side effects (nausea and vomiting occur in ~10–15% of children). 1, 4, 5
- Timing: Ideally, treatment should have been initiated within 48 hours of symptom onset for maximum benefit; earlier initiation (within 12–24 hours) provides even greater symptom reduction. 1, 4, 5
- Complete the full course: Continue for the entire 5 days even if symptoms improve earlier—early discontinuation may promote viral resistance. 1, 3
Dispensing Information
- You will need to dispense 2 bottles of the oral suspension (each bottle contains 60 mL when reconstituted to 6 mg/mL). 3
- Each 7.5 mL dose × 2 doses/day × 5 days = 75 mL total volume required. 3
Critical Pitfalls to Avoid
- Do not round down to 30 mg: A common prescribing error is using the ≤15 kg dose (30 mg) for a child who weighs 16.69 kg. This patient is in the next weight bracket and requires 45 mg. 1, 2
- Do not use age-based dosing alone: Weight-based categorical dosing takes precedence over age for children ≥12 months. 1, 2, 6
- Do not confuse treatment with prophylaxis dosing: Treatment is twice daily; prophylaxis (not indicated here) would be once daily. 1, 3
- Do not adjust for renal function unless impaired: No dose adjustment is needed for normal renal function; reduction is only required if creatinine clearance is <30 mL/min. 1, 3
Monitoring and Safety
- Common adverse effects: Nausea, vomiting, and diarrhea are typically mild, transient, and resolve within 1–2 days. 1, 4, 5
- No difference between influenza A and B: The same dosing regimen applies to both influenza types. 1, 3, 5
- Resistance is rare: Oseltamivir resistance in influenza B is uncommon and of minimal clinical concern. 4, 7