What is the recommended dose of Tamiflu (oseltamivir) for a 9.83kg patient with influenza?

Tamiflu Dosing for a 9.83kg Patient

For a patient weighing 9.83 kg, administer oseltamivir 30 mg (5 mL of oral suspension) twice daily for 5 days for treatment, or 30 mg once daily for 10 days for prophylaxis. 1, 2, 3

Weight-Based Dosing Algorithm

This patient falls into the ≤15 kg weight category, which is the critical determinant for dosing in pediatric patients. 1, 2, 3

Treatment Dosing (5 days)

• 30 mg (5 mL of 6 mg/mL oral suspension) twice daily for 5 days 1, 2, 3
• Initiate treatment within 48 hours of symptom onset for maximum effectiveness 1, 2, 4

Prophylaxis Dosing (10 days post-exposure)

• 30 mg (5 mL of 6 mg/mL oral suspension) once daily for 10 days 1, 2, 3
• Begin within 48 hours following close contact with an infected individual 2, 4

Formulation and Administration

• Use the oral suspension formulation at 6 mg/mL concentration 2, 4, 3
• The 30 mg dose equals exactly 5 mL of properly reconstituted oral suspension 2, 4, 3
• Administer with food to reduce gastrointestinal side effects (nausea and vomiting occur in approximately 5-15% of patients but are significantly reduced when taken with food) 4, 5
• Use a calibrated oral dosing syringe to ensure accurate measurement of the 5 mL volume 2

Critical Pitfalls to Avoid

Do NOT round up to the next weight category. A patient weighing 9.83 kg should receive 30 mg, not 45 mg, as they remain well below the 15 kg threshold for the next dosing tier. 2 The weight categories are: ≤15 kg (30 mg), >15-23 kg (45 mg), >23-40 kg (60 mg), and >40 kg (75 mg). 2, 4, 3

Verify the patient's age is ≥1 year for prophylaxis. Oseltamivir prophylaxis is only indicated for patients 1 year and older, though treatment can be given to patients as young as 2 weeks. 1, 3 If this patient is under 1 year of age, prophylaxis is not recommended unless the situation is judged critical. 4

Renal Function Considerations

For this pediatric patient, no dose adjustment is needed unless creatinine clearance is <30 mL/min. 2, 4 Standard dosing applies for normal renal function. 2

Monitoring and Adverse Effects

• Monitor for nausea and vomiting, the most common adverse effects, which are typically mild and transient 4, 5, 6
• Gastrointestinal symptoms are significantly less likely when oseltamivir is taken with food 4, 5
• Complete the full 5-day treatment course even if symptoms improve earlier 2
• Only approximately 1% of patients discontinue oseltamivir due to gastrointestinal side effects 4

Clinical Context

This dosing applies whether the patient has confirmed influenza A or B infection. 3 The same weight-based dose (30 mg) is used regardless of influenza strain. 1, 2, 3