What is the recommended dose of Tamiflu (Oseltamivir) for an 18-month-old child?

Tamiflu Dosing for an 18-Month-Old Child

For an 18-month-old child, administer oseltamivir 30 mg twice daily for 5 days if the child weighs ≤15 kg (≤33 lb), or 45 mg twice daily if the child weighs >15-23 kg (33-51 lb), using the oral suspension formulation (6 mg/mL concentration). 1, 2

Weight-Based Dosing Algorithm

At 18 months of age, children fall into the ≥12 months category and require weight-based dosing rather than age-based dosing:

• If weight ≤15 kg (≤33 lb): 30 mg twice daily = 5 mL of oral suspension twice daily for 5 days 1, 2
• If weight >15-23 kg (33-51 lb): 45 mg twice daily = 7.5 mL of oral suspension twice daily for 5 days 1, 2
• If weight >23-40 kg (51-88 lb): 60 mg twice daily = 10 mL of oral suspension twice daily for 5 days 1, 2

The most critical step is to verify the child's current weight before prescribing to avoid dosing errors. 3

Formulation and Administration

• Use the oral suspension formulation (6 mg/mL concentration after reconstitution by the pharmacist) 1, 2
• Administer with food to improve gastrointestinal tolerability, as nausea and vomiting are common adverse effects 1, 4
• Use an accurate oral dosing syringe or measuring device to ensure precise volume measurement 2

Critical Timing Considerations

Treatment must be initiated within 48 hours of symptom onset for maximum effectiveness. 4, 5, 2 Earlier initiation is associated with faster symptom resolution and better clinical outcomes 6

Common Pitfalls to Avoid

• Do not use age-based dosing (3 mg/kg) for children ≥12 months old - this dosing is reserved for infants <12 months 1, 2
• Do not assume weight - always verify current weight as children at 18 months can vary significantly in size 3
• Do not delay treatment waiting for laboratory confirmation in high-risk patients or those with severe symptoms 4

Prophylaxis Dosing (If Needed)

For post-exposure prophylaxis following close contact with an infected individual:

• Same weight-based doses as treatment, but given once daily instead of twice daily for 10 days 1, 2
• Must be initiated within 48 hours of exposure 2

Special Considerations

• No renal dose adjustment needed unless the child has moderate to severe renal impairment (creatinine clearance 10-30 mL/min), in which case reduce to once daily dosing 1, 4
• The standard 5-day treatment duration applies regardless of weight category 1, 3
• Oseltamivir is FDA-approved for treatment in children as young as 2 weeks of age 1, 5, 2