Yes you can take Emergen C everyday if you have a cold or flu virus to help ease the symptoms and help get rid of the flu virus or cold virus much sooner.
If you're not sick with the cold or flu virus then you should not take take Emergen C everyday as it could harm you when you take too much of the Emergen C.
However when you have the flu and cold viruses you can take Emergen C everyday for as long as you have the cold or flu virus.
The Emergen C helps to ease the symptoms of the cold and flu virus but it's not a cure for a cold or flu virus as there are no cures for the cold or flu.
But the cold medicine and flu medicine Emergen C and Airborne can help ease the symptoms and make you feel better sooner.