how long before flu symptoms appear?
Symptoms of the Flu: An Overview. It's easy to confuse a common cold with flu symptoms. However, cold symptoms are usually milder and don't last as long as the flu symptoms. If you become infected with the flu virus, you will usually feel flu symptoms 1 to 4 days later. It is important to note that you can spread the flu to others before your flu symptoms start and for another 3 to 4 days after your flu symptoms appear. (Click Flu Virus for more information about the flu.)