Flu Cough Contagious After 10 Days? Understanding the Timeline

It depends on the individual's immune system and the severity of the flu. The flu is typically most contagious in the first 3-4 days of symptoms, but can be spread up to 7 days after symptoms begin. In some cases, people may be contagious for longer if they have a weakened immune system or a more severe case of the flu. To be safe, it is best to assume that you are contagious until you have been fever-free for at least 24 hours.