What is the recommended dose of Tamiflu (oseltamivir) for prophylaxis in individuals exposed to the flu?

Tamiflu (Oseltamivir) Prophylaxis Dosing

For post-exposure prophylaxis in adults and adolescents ≥13 years, administer oseltamivir 75 mg orally once daily for 10 days, initiated within 48 hours of exposure to an infected individual. 1, 2

Adult and Adolescent Dosing (≥13 years)

• Standard prophylaxis dose: 75 mg once daily (12.5 mL of oral suspension if using liquid formulation) 1, 2
• Duration varies by indication:
  • Post-exposure prophylaxis: 10 days following close contact with infected individual 1, 2
  • Seasonal/community outbreak prophylaxis: Up to 6 weeks during influenza activity 2
  • Immunocompromised patients: May extend up to 12 weeks 2
• Protection lasts only as long as medication is continued 2

Pediatric Prophylaxis Dosing (≥1 year to 12 years)

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

• ≤15 kg (≤33 lb): 30 mg once daily (5 mL oral suspension)
• >15-23 kg (>33-51 lb): 45 mg once daily (7.5 mL oral suspension)
• >23-40 kg (>51-88 lb): 60 mg once daily (10 mL oral suspension)
• >40 kg (>88 lb): 75 mg once daily (12.5 mL oral suspension)

Infant Prophylaxis (3-11 months)

• Dose: 3 mg/kg once daily for 10 days 1, 4
• Prophylaxis is not recommended for infants <3 months unless the situation is judged critical due to limited safety data 5, 1

Renal Impairment Adjustments

For patients with creatinine clearance 10-30 mL/min: 5, 1, 4

• Option 1: 30 mg once daily for 10 days
• Option 2: 75 mg every other day for 10 days (5 total doses)
• Oseltamivir is not recommended for end-stage renal disease patients not on dialysis 2

Critical Timing Considerations

• Initiate prophylaxis within 48 hours of exposure to maximize effectiveness 1, 6
• Earlier initiation provides better protection 6
• Prophylaxis should be started promptly after close contact with confirmed or suspected influenza cases 4, 6

Efficacy Data

• Protective efficacy: 67-89% against laboratory-confirmed influenza when used for prophylaxis 7, 8, 6
• In household contacts, oseltamivir demonstrated 89% protective efficacy for individuals and 84% for households 6
• A 3-day regimen showed 93% protective efficacy in hospital ward settings, though this is not FDA-approved 9

Administration Pearls

• May be taken with or without food, though taking with food improves gastrointestinal tolerability 1, 2
• Nausea and vomiting occur in approximately 5-15% of patients but are reduced when taken with meals 1
• Available as capsules (30,45,75 mg) or oral suspension (6 mg/mL when reconstituted) 1, 2

Special Populations

Pregnancy

• Same dosing as non-pregnant adults: 75 mg once daily 4
• Oseltamivir is preferred over zanamivir in pregnancy 4
• Benefits outweigh risks given increased complications from influenza during pregnancy 4

Immunocompromised Patients

• May require extended prophylaxis up to 12 weeks during community outbreaks 2
• Standard dosing applies unless renal impairment present 4

Important Caveats

• Prophylaxis is not a substitute for annual influenza vaccination 2
• Avoid live attenuated influenza vaccine (LAIV) within 48 hours before oseltamivir; do not use oseltamivir for 14 days after LAIV 1
• Consider prophylaxis primarily for high-risk individuals (elderly, chronic disease, immunocompromised) and unvaccinated persons during outbreaks 4, 10
• Limit use to situations with clear benefit to avoid resistance development 10