What is the preventative dose of Tamiflu (oseltamivir) for influenza?

Preventative Dose of Tamiflu (Oseltamivir)

For adults and adolescents ≥13 years, the preventative dose of oseltamivir is 75 mg once daily for at least 10 days following exposure to an infected individual, or up to 6 weeks during a community outbreak. 1, 2, 3

Adult and Adolescent Prophylaxis Dosing

• The standard prophylaxis dose is 75 mg orally once daily (12.5 mL of oral suspension if using liquid formulation) 1, 2, 3
• Duration depends on the prophylaxis scenario:
  • Post-exposure prophylaxis: 10 days after close contact with an infected individual 1, 2, 3
  • Seasonal/community outbreak prophylaxis: Up to 6 weeks during periods of local influenza activity 2, 3
  • Immunocompromised patients: May extend up to 12 weeks during community outbreaks 2, 3

Pediatric Prophylaxis Dosing (≥1 year)

Weight-based dosing once daily for 10 days following exposure: 1, 2, 3

• ≤15 kg: 30 mg once daily (5 mL oral suspension) 1, 2, 3
• >15-23 kg: 45 mg once daily (7.5 mL oral suspension) 1, 2, 3
• >23-40 kg: 60 mg once daily (10 mL oral suspension) 1, 2, 3
• >40 kg: 75 mg once daily (12.5 mL oral suspension) 1, 2, 3

For seasonal prophylaxis during community outbreaks, the same weight-based doses are used but may be continued for up to 6 weeks. 2, 3

Infants (3-11 months)

• 3 mg/kg once daily for 10 days following exposure 1, 2
• Prophylaxis is not recommended for infants <3 months unless the situation is judged critical due to limited safety data 1

Critical Timing Considerations

• Initiate prophylaxis within 48 hours of exposure to an infected individual for post-exposure prophylaxis 1, 2
• The protective effect lasts only as long as oseltamivir is being taken; protection does not persist after discontinuation 2, 3

Renal Impairment Adjustments

For patients with creatinine clearance 10-30 mL/min: 1, 2, 3

• 30 mg once daily for 10 days, OR
• 75 mg every other day for 10 days (5 total doses)

Administration Considerations

• Can be taken with or without food, though taking with food may reduce nausea 1, 3
• Nausea is more common with prophylactic dosing compared to treatment dosing (occurs in approximately 1 in 7 patients on prophylaxis) 1

Drug Interaction Warning

• Avoid live attenuated influenza vaccine (LAIV) within 48 hours before starting oseltamivir 1, 2
• Do not use oseltamivir for 14 days after LAIV vaccination, as the antiviral may interfere with vaccine effectiveness 1, 2

Efficacy Data

• Post-exposure prophylaxis demonstrates 58.5% to 89% protective efficacy in household contacts and exposed individuals 4, 5
• Seasonal prophylaxis in unvaccinated adults shows >70% protection against naturally acquired influenza during community outbreaks 4
• In previously vaccinated high-risk elderly patients, oseltamivir provides 92% protective efficacy when used adjunctively 4

Common Pitfall

A critical error is confusing prophylaxis dosing (once daily) with treatment dosing (twice daily). The prophylaxis dose is half the treatment dose frequency but uses the same mg amount per dose. 1, 2, 3