What is the recommended dosage of Tamiflu (oseltamivir) for prophylaxis in a 2-year-old child weighing 11.5 kg?

Tamiflu Dosing for Prophylaxis in a 2-Year-Old Weighing 11.5 kg

For a 2-year-old child weighing 11.5 kg, administer Tamiflu 30 mg (5 mL of oral suspension) once daily for 10 days for influenza prophylaxis. 1

Weight-Based Dosing Algorithm

This child falls into the ≤15 kg weight category, which determines the prophylaxis dose:

• Children weighing ≤15 kg: 30 mg once daily for 10 days 1, 2
• Children >15-23 kg: 45 mg once daily 1
• Children >23-40 kg: 60 mg once daily 1
• Children >40 kg: 75 mg once daily 1

Critical pitfall to avoid: Do not round up to the next weight category. At 11.5 kg, this patient remains in the ≤15 kg bracket and should receive 30 mg, not 45 mg. 2

Formulation and Administration

• Use the oral suspension formulation at 6 mg/mL concentration 1, 3
• Administer 5 mL once daily to deliver the 30 mg dose 1, 3
• Use a calibrated oral dosing device that accurately measures 5 mL 2, 3
• May be given with or without food, though administration with food improves gastrointestinal tolerability 1, 4

If commercial suspension is unavailable, pharmacies can compound it to the same 6 mg/mL concentration based on package insert instructions. 1, 4

Timing and Duration

• Initiate prophylaxis within 48 hours following close contact with an infected individual 1, 3
• Standard duration: 10 days for post-exposure prophylaxis 1, 3
• Extended duration: Up to 6 weeks during community outbreaks 1, 3

Renal Function Considerations

For this age and assuming normal renal function, no dose adjustment is needed. 2 However, if creatinine clearance were 10-30 mL/min, the dose would require reduction to 30 mg every other day for 10 days. 1, 4

Monitoring for Adverse Effects

• Gastrointestinal symptoms (nausea, vomiting) occur in approximately 10-15% of patients but are typically mild and transient 4, 5
• These effects are significantly reduced when oseltamivir is taken with food 4, 6
• Only approximately 1% of patients discontinue therapy due to gastrointestinal side effects 4
• Monitor for headache and skin reactions, which may occur but are generally mild 2

Key Clinical Context

This dosing applies to children ≥12 months of age. 1, 2 At 2 years of age, this patient is well within the standard pediatric weight-based dosing category. The weight-based algorithm takes precedence over age-based recommendations for children in this age range. 2