Tamiflu Dosing for an 85.2 kg Child
For a child weighing 85.2 kg, the recommended Tamiflu dose is 75 mg twice daily for treatment (5 days) or 75 mg once daily for prophylaxis (10 days). 1
Weight-Based Dosing Algorithm
The dosing of oseltamivir in children follows a strict weight-based approach that has remained consistent across multiple guideline iterations:
- ≤15 kg: 30 mg twice daily (treatment) or 30 mg once daily (prophylaxis) 1
- >15-23 kg: 45 mg twice daily (treatment) or 45 mg once daily (prophylaxis) 1
- >23-40 kg: 60 mg twice daily (treatment) or 60 mg once daily (prophylaxis) 1
- >40 kg: 75 mg twice daily (treatment) or 75 mg once daily (prophylaxis) 1
Application to This Patient
Since this child weighs 85.2 kg, which exceeds 40 kg (88 lb), they fall into the highest weight category and should receive the adult dose of 75 mg. 1 This dosing has been consistently recommended across guidelines from 2001 through 2024. 1
Formulation Options
For a child of this weight, capsule formulation is appropriate:
- Capsules: Available as 30 mg, 45 mg, or 75 mg strengths 1
- Oral suspension: If capsules cannot be swallowed, the 75 mg dose equals 12.5 mL of the 6 mg/mL suspension 1
Treatment Duration
- Treatment course: 75 mg twice daily for 5 days 1
- Prophylaxis: 75 mg once daily for 10 days after exposure, or up to 6 weeks during community outbreaks 1
Administration Considerations
Oseltamivir should be administered without regard to meals, though taking it with food may reduce gastrointestinal side effects such as nausea and vomiting. 1 These gastrointestinal events are typically mild and transient. 2
Common Pitfalls to Avoid
Do not underdose based on age alone. Even though this is a "child," the weight of 85.2 kg places them firmly in the adult dosing category. 1 The weight-based algorithm supersedes age considerations once a patient exceeds 40 kg. 1
Ensure renal function is normal. If creatinine clearance is 10-30 mL/min, reduce the treatment dose to 75 mg once daily for 5 days, or for prophylaxis use 30 mg once daily for 10 days or 75 mg every other day for 10 days (5 total doses). 1
Complete the full treatment course even if symptoms improve earlier, as premature discontinuation may contribute to incomplete viral clearance. 2