Comfortis is a chewable tablet that is given orally with food for maximum effectiveness. If vomiting occurs within one hour of administration, redose with another full dose. Comfortis is preferably started one month before fleas become active and should be given monthly through the end of the flea season. In areas where fleas are common year-round, monthly treatment should continue the entire year without interruption. This medication should only be given to the pet for whom it was prescribed.