How long are you contagious when you have the flu? if someone doesn't have the flu but someone living with them does, can taking tamiflu help prevent

Tamiflu can prevent.: Nobody really knows when one person stops being contagious with influenza (with or without Tamiflu treatment). One week out from the start of the illness (one can count from the first day of fever, aches, or cough) is safe, unless a person had a more severe illness or still has a lot of cough. In a more severe case, one can take longer, such as until 3 more days after no fever nor excessive cough.