What is the recommended form and dosage of Tamiflu (oseltamivir) for adults, tablet or suspension?

Tamiflu Formulation for Adults

For adults, both the 75 mg capsule and oral suspension (6 mg/mL) are equally appropriate formulations of oseltamivir, with the capsule being the standard choice for those who can swallow pills, and the suspension reserved for patients who cannot swallow capsules or prefer liquid medication. 1

Standard Adult Dosing

Treatment Regimen:

• 75 mg orally twice daily for 5 days for adults and adolescents ≥13 years 2, 3, 1
• Initiate within 48 hours of symptom onset for maximum benefit 3, 1
• Can be taken with or without food, though administration with meals may reduce gastrointestinal side effects like nausea and vomiting 2, 4, 1

Prophylaxis Regimen:

• 75 mg orally once daily for at least 10 days following exposure or up to 6 weeks during community outbreaks 2, 3, 1
• Start within 48 hours of close contact with an infected individual 5, 1

Available Formulations

Capsule Form:

• Available in 30 mg, 45 mg, and 75 mg strengths 2, 3, 1
• The 75 mg capsule is the standard formulation for adults 1

Oral Suspension:

• Supplied as powder that must be reconstituted by pharmacist to 6 mg/mL concentration 2, 3, 1
• For a 75 mg adult dose, administer 12.5 mL of the 6 mg/mL suspension 2, 1
• If capsules cannot be swallowed, they can be opened and contents mixed with sweetened liquid to mask bitter taste 2
• Retail pharmacies can compound suspension if commercial product unavailable 2

Renal Impairment Adjustments

For creatinine clearance 10-30 mL/min:

• Treatment: 75 mg once daily (instead of twice daily) for 5 days 2, 3, 4
• Prophylaxis: 30 mg once daily for 10 days OR 75 mg every other day for 10 days (5 total doses) 2, 3, 4
• Oseltamivir is not recommended for end-stage renal disease patients not on dialysis 1

Clinical Pearls and Common Pitfalls

Timing is Critical:

• Do not delay treatment waiting for laboratory confirmation in high-risk patients—start empirically based on clinical suspicion 3
• Treatment initiated after 48 hours may still provide benefit in hospitalized or high-risk patients, though optimal benefit occurs within the first 48 hours 3, 6

Dosing Errors to Avoid:

• Do not confuse prophylaxis dosing (75 mg once daily) with treatment dosing (75 mg twice daily)—this is a common prescribing error 5
• Ensure proper dose adjustment in renal impairment to avoid toxicity 4, 1

Drug Interactions:

• Avoid live attenuated influenza vaccine (LAIV) within 48 hours before oseltamivir use 3
• Do not use oseltamivir for 14 days after LAIV vaccination, as it may interfere with vaccine efficacy 3, 4

Tolerability:

• Nausea and vomiting occur in approximately 5-15% of patients but are typically mild and transient 4, 6
• Taking with food significantly reduces gastrointestinal side effects without affecting drug absorption 2, 4, 6