If i already have the flu, how do i know when i cease being contagious ?

Fever: The viremic phase of most viral illnesses, usually marker by fever and other discomfort, is the time when most infectious processes are most contagious , as in the case of influenza. The end of the viremic phase is usually brought on by the lack of fever and/or a rash, among other symptoms. I believe if the fever is gone and respiratory symptoms have improved are good signs you are non-infectious