 A multi-centre, randomized, placebo controlled, trial. Participants will be patients either 65 years or with one or more high risk conditions presenting to one of four academic emergency departments in Edmonton or Calgary with influenza-like illness. The investigators will test for influenza using a point-of-care rapid test and if positive for influenza participants will be randomized to oseltamivir or placebo and followed prospectively. The primary outcome will be hospitalization. 