Oseltamivir is an antiviral medication used to treat and prevent influenza A and influenza B. Many medical organizations recommend it in people who have complications or are at high risk of complications within 48 hours of first symptoms of infection.

Oseltamivir phosphate is an oral anti-viral drug approved for the treatment of acute, uncomplicated influenza in patients 2 weeks of age and older whose flu symptoms have not lasted more than two days.