How long is a person with upper respiratory flu contagious for?

A person with an upper respiratory flu, such as influenza, is typically contagious for about 1 day before symptoms appear and can remain contagious for up to 5 to 7 days after becoming symptomatic. Children and individuals with weakened immune systems may be contagious for a longer period. It's important to practice good hygiene to help prevent the spread of the virus during this time.