Tamiflu drug molecule, computer model. Tamiflu (oseltamivir phosphate) is an anti-viral drug used to treat influenza. Atoms are colour-coded: carbon (pink), hydrogen (grey), oxygen (green), nitrogen (red), phosphorus (blue). The oseltamivir molecule (C16.H28.N2.O4) is seen with a phosphate ion (P.O4.H3, left). Tamiflu inhibits neuraminidase, a surface protein of the influenza viruses. Tamiflu is taken orally and may reduce the symptoms of an influenza infection, as well as preventing initial infections. In 2005, the drug was being stockpiled as part of preparations for a possible pandemic of avian influenza. Tamiflu is manufactured by Roche Pharmaceuticals.