Oseltamivir Dosing Recommendations
For treatment of influenza, adults and adolescents ≥13 years should receive oseltamivir 75 mg orally twice daily for 5 days, initiated within 48 hours of symptom onset for maximum efficacy. 1, 2, 3
Adult and Adolescent Treatment Dosing (≥13 years)
- Standard dose: 75 mg orally twice daily for 5 days 1, 2, 4, 3
- Treatment should be initiated within 48 hours of symptom onset, though earlier initiation (within 12-24 hours) provides greater benefit 1, 5
- Can be taken with or without food, though administration with food improves gastrointestinal tolerability 1, 3, 5
Pediatric Treatment Dosing
Children ≥12 months (weight-based dosing preferred):
- ≤15 kg (≤33 lb): 30 mg twice daily for 5 days 1, 2, 4, 3
- >15-23 kg (>33-51 lb): 45 mg twice daily for 5 days 1, 2, 4, 3
- >23-40 kg (>51-88 lb): 60 mg twice daily for 5 days 1, 2, 4, 3
- >40 kg (>88 lb): 75 mg twice daily for 5 days 1, 2, 4, 3
Infants <12 months:
- 9-11 months: 3.5 mg/kg per dose twice daily for 5 days 1, 2, 4
- Term infants 0-8 months: 3 mg/kg per dose twice daily for 5 days 1, 2, 4
Preterm infants (based on postmenstrual age):
- <38 weeks postmenstrual age: 1.0 mg/kg twice daily for 5 days 1, 2, 4
- 38-40 weeks postmenstrual age: 1.5 mg/kg twice daily for 5 days 1, 2, 4
- >40 weeks postmenstrual age: 3.0 mg/kg twice daily for 5 days 1, 2, 4
Prophylaxis Dosing
Adults and Adolescents (≥13 years):
- 75 mg orally once daily for 10 days (post-exposure prophylaxis) 1, 2, 3
- 75 mg orally once daily for up to 6 weeks (seasonal prophylaxis during community outbreak) 1, 2, 3
- Immunocompromised patients: may continue for up to 12 weeks 3
Pediatric Patients (≥1 year):
- Use same weight-based doses as treatment, but once daily instead of twice daily for 10 days 1, 2, 3
- Seasonal prophylaxis: continue for up to 6 weeks during community outbreak 1, 3
Infants 3-11 months:
- 3 mg/kg once daily for 10 days 1, 2
- Prophylaxis not recommended for infants <3 months unless situation is critical due to limited safety data 1
Renal Impairment Adjustments
Creatinine clearance 10-30 mL/min:
- Treatment: 75 mg once daily for 5 days 1, 2, 4
- Prophylaxis: 30 mg once daily for 10 days OR 75 mg every other day for 10 days (5 total doses) 1, 2
Formulation and Administration
Available formulations:
- Capsules: 30 mg, 45 mg, 75 mg 1, 2, 4, 3
- Oral suspension: 6 mg/mL when reconstituted (preferred for patients who cannot swallow capsules) 1, 2, 3
Suspension dosing volumes:
- 30 mg dose = 5 mL 1, 2, 3
- 45 mg dose = 7.5 mL 1, 2, 3
- 60 mg dose = 10 mL 1, 2, 3
- 75 mg dose = 12.5 mL 1, 2, 3
Administration tips:
- Capsules can be opened and contents mixed with liquid if patient cannot swallow whole 1
- If commercial suspension unavailable, pharmacies can compound using capsule contents mixed with simple syrup or Ora-Sweet SF to achieve 6 mg/mL concentration 1
Special Populations
Pregnancy:
- Pregnant women receive same dosing as non-pregnant adults: 75 mg twice daily for 5 days 2
- No contraindication exists for oseltamivir use in pregnancy, and benefit-risk profile strongly favors treatment 2
- Oseltamivir is preferred over zanamivir in pregnancy 2
Breastfeeding:
- Breastfeeding mothers should receive oseltamivir as indicated; not a reason to discontinue breastfeeding 2
Critical Clinical Pearls
Timing considerations:
- Initiate treatment within 48 hours of symptom onset for efficacy 1, 3, 5
- Earlier initiation (within 12 hours) reduces illness duration by an additional 74.6 hours compared to treatment at 48 hours 5
- Do not wait for laboratory confirmation in high-risk patients; initiate empiric treatment 1
Drug interactions:
- Avoid live attenuated influenza vaccine (LAIV) within 48 hours before oseltamivir 1, 2
- Do not use oseltamivir for 14 days after LAIV vaccination 1, 2
Common adverse effects:
- Nausea and vomiting occur in approximately 10% of patients, typically mild and transient 1, 6, 5
- Taking with food significantly reduces gastrointestinal adverse effects 1, 3, 5
- Gastrointestinal effects rarely result in discontinuation 6, 7