What is the recommended dose of Tamiflu (Oseltamivir) for influenza treatment?

Tamiflu (Oseltamivir) Dosing

For adults and adolescents ≥13 years, the standard treatment dose is 75 mg orally twice daily for 5 days, and for prophylaxis, 75 mg once daily for 10 days (post-exposure) or up to 6 weeks (seasonal). 1, 2

Treatment Dosing

Adults and Adolescents (≥13 years)

• 75 mg orally twice daily for 5 days 1, 2
• Initiate treatment within 48 hours of symptom onset for maximum effectiveness 3, 4
• Earlier initiation (within 12 hours) reduces illness duration by an additional 3.1 days compared to treatment at 48 hours 4

Pediatric Patients (≥12 months)

Weight-based dosing twice daily for 5 days: 1, 3

• ≤15 kg (≤33 lb): 30 mg twice daily
• >15-23 kg (>33-51 lb): 45 mg twice daily
• >23-40 kg (>51-88 lb): 60 mg twice daily
• >40 kg (>88 lb): 75 mg twice daily

Infants (Birth to <12 months)

• 9-11 months: 3.5 mg/kg per dose twice daily for 5 days 1
• Term infants 0-8 months: 3 mg/kg per dose twice daily for 5 days 1
• Infants <3 months: Use only in critical situations due to limited safety data 1

Preterm Infants

Dosing based on postmenstrual age (gestational age + chronological age): 1, 3

• <38 weeks: 1.0 mg/kg twice daily for 5 days
• 38-40 weeks: 1.5 mg/kg twice daily for 5 days
• >40 weeks: 3.0 mg/kg twice daily for 5 days
• Lower doses are essential due to immature renal function and risk of drug accumulation 1

Prophylaxis Dosing

Adults and Adolescents (≥13 years)

• 75 mg once daily for 10 days (post-exposure prophylaxis) 1, 2
• 75 mg once daily for up to 6 weeks (seasonal prophylaxis) 1, 2
• Up to 12 weeks in immunocompromised patients 3, 2
• Initiate within 48 hours of exposure to infected individual 2

Pediatric Patients (≥1 year)

Same weight-based doses as treatment, but once daily instead of twice daily for 10 days: 1, 3

• ≤15 kg: 30 mg once daily
• >15-23 kg: 45 mg once daily
• >23-40 kg: 60 mg once daily
• >40 kg: 75 mg once daily

Infants (3-11 months)

• 3 mg/kg once daily for 10 days 3
• Not recommended for infants <3 months unless critical situation 1

Renal Impairment Adjustments

Treatment

• Creatinine clearance 10-30 mL/min: 75 mg once daily for 5 days 1, 3

Prophylaxis

• Creatinine clearance 10-30 mL/min: 30 mg once daily for 10 days OR 75 mg every other day for 10 days (5 total doses) 1, 3

End-Stage Renal Disease

• Not recommended for patients not undergoing dialysis 2

Formulation and Administration

Available Forms

• Capsules: 30 mg, 45 mg, 75 mg 1, 2
• Oral suspension: 6 mg/mL when reconstituted 1, 2

Suspension Dosing Volumes (6 mg/mL concentration)

• 30 mg dose = 5 mL 1
• 45 mg dose = 7.5 mL 1
• 60 mg dose = 10 mL 1
• 75 mg dose = 12.5 mL 1

Administration Tips

• Can be taken with or without food 1, 2
• Taking with food improves gastrointestinal tolerability and reduces nausea/vomiting 1, 3, 5
• Use appropriate oral dosing device that accurately measures volume in mL 2
• For infants requiring weight-based dosing, ensure dosing device can measure small volumes accurately 2

Clinical Pearls

Timing Considerations

• Treatment initiated within 12 hours of symptom onset provides 40% reduction in illness duration compared to 48-hour initiation 6
• Benefits are progressive—every hour earlier increases therapeutic effect 4

Common Adverse Effects

• Nausea and vomiting are most common (occur in 1 in 7 patients vs 1 in 12 on placebo) 7
• Gastrointestinal effects are typically mild, transient, and occur mainly with first dose 5, 4
• Taking with food significantly reduces these effects 5, 4
• Discontinuation rate is low (1.8%) 4

Drug Interactions

• Avoid live attenuated influenza vaccine (LAIV) within 48 hours before oseltamivir 3
• Do not use oseltamivir for 14 days after LAIV vaccination 3

Resistance Considerations

• Oseltamivir remains effective against most circulating strains 1
• Amantadine and rimantadine should not be used due to high resistance rates 1
• Shorter durations or lower doses than recommended may promote resistance emergence 8