Tamiflu Dosing for a 9-Year-Old Child
For a 9-year-old child with influenza, administer oseltamivir (Tamiflu) based on body weight: 30 mg twice daily for children ≤15 kg, 45 mg twice daily for 15.1-23 kg, 60 mg twice daily for 23.1-40 kg, or 75 mg twice daily for children >40 kg, given orally for 5 days. 1, 2
Weight-Based Dosing for Treatment
The American Academy of Pediatrics recommends the following weight-based treatment regimen for children aged 1-12 years 1, 2:
- ≤15 kg (≤33 lb): 30 mg twice daily for 5 days 1
- >15-23 kg (33-51 lb): 45 mg twice daily for 5 days 1
- >23-40 kg (51-88 lb): 60 mg twice daily for 5 days 1
- >40 kg (>88 lb): 75 mg twice daily for 5 days 1
Most 9-year-olds typically weigh between 23-40 kg, making the 60 mg twice daily dose most common for this age group, though you must verify the child's actual weight to determine the correct dose. 2
Formulation and Administration
Oseltamivir is available in multiple formulations 1, 3:
- Capsules: 30 mg, 45 mg, and 75 mg strengths 1, 3
- Oral suspension: 6 mg/mL concentration when reconstituted 1, 3
For the oral suspension dosing volumes 2, 3:
- 30 mg dose = 5 mL
- 45 mg dose = 7.5 mL
- 60 mg dose = 10 mL
- 75 mg dose = 12.5 mL
Administration with food may improve gastrointestinal tolerability, as nausea and vomiting occur in approximately 1 in 7 treated patients. 1, 2, 4
Critical Timing Considerations
Treatment must be initiated within 48 hours of symptom onset for maximum effectiveness. 1, 2, 3 Earlier initiation is associated with faster symptom resolution and greater reduction in illness duration (up to 1.5 days). 4, 5
However, do not withhold treatment in high-risk patients even if presenting beyond 48 hours, as benefits still exist for hospitalized or immunocompromised children. 2
Prophylaxis Dosing (If Applicable)
If prescribing for post-exposure prophylaxis rather than treatment, use the same weight-based doses but once daily instead of twice daily for 10 days following close contact with an infected individual 1, 2:
- ≤15 kg: 30 mg once daily 1
15-23 kg: 45 mg once daily 1
23-40 kg: 60 mg once daily 1
40 kg: 75 mg once daily 1
Prophylaxis should be initiated within 48 hours of exposure. 2
Special Considerations and Caveats
Renal impairment requires dose adjustment. For children with creatinine clearance 10-30 mL/min, reduce the treatment dose to once daily instead of twice daily. 1, 2
Common pitfall: Do not delay treatment while waiting for laboratory confirmation in suspected influenza cases, as rapid antigen tests have poor sensitivity and treatment benefit is time-dependent. 2
Tolerability: Gastrointestinal side effects (nausea, vomiting, diarrhea) are the most common adverse events but are typically mild and transient. 1, 4, 6 Taking the medication with food significantly reduces these symptoms. 1, 2
Drug interaction: Avoid live attenuated influenza vaccine (LAIV) within 48 hours before oseltamivir use, and do not use oseltamivir for 14 days after LAIV vaccination. 2