Oseltamivir Phosphate (Tamiflu) Uses

Oseltamivir phosphate is used to treat uncomplicated influenza in adults, children, and infants 2 weeks of age and older who have had flu symptoms for less than 48 hours. It is also used to prevent infection with the influenza virus types A and B in adults and children 1 year of age and older during a flu outbreak or after a person has spent time with someone who has flu symptoms. However, oseltamivir phosphate is not a substitute for the yearly flu vaccine. Also, this medication cannot prevent or treat bacterial infections.

There may be other uses of oseltamivir phosphate—your pharmacist or doctor can give you further drug information.

Oseltamivir Phosphate (Tamiflu) Mechanism of Action

Oseltamivir phosphate is a prodrug of the neuraminidase inhibitor oseltamivir carboxylate which is the active metabolite. It works by preventing the flu virus from making copies of itself and spreading in the body.

Oseltamivir Phosphate (Tamiflu) Doses

For treatment of influenza:

• Adults and adolescents (13 years of age and older): 75 mg twice daily for 5 days.
• Pediatric patients (1 to 12 years of age): The dose depends on the child’s body weight, and the medicine is given twice daily for 5 days.
• Pediatric patients (2 weeks to less than 1 year of age): 3 mg/kg twice daily for 5 days.

Note: A lower dose is prescribed to patients with renal impairment (reduced kidney function). 

For prevention of influenza:

• Adults and adolescents (13 years and older): 75 mg once daily for a minimum of 10 days.
• Pediatric patients (1 to 12 years of age): The dose depends on the child’s body weight, and the medicine is given once daily for 10 days.

Note: In case of a community outbreak, oseltamivir may be prescribed once daily for up to 6 weeks in both adults and pediatric patients and up to 12 weeks in immunocompromised patients.