After taking tamiflu (oseltamivir) how long am i contagious?

5 days once sick: According to the centers for disease control and prevention (cdc), most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Tamiflu (oseltamivir) may shorten this by a day, but there is actually little data looking at your question. Some say you can't spread it 24 hrs after your last fever, but that is false.