Advantage Flea Control for Cats 1-9 lbs 4 Month Supply Advantage Flea Control is a monthly application that kills 98% to 100% of fleas and their larvae within 12 hours. re-infesting fleas are killed within 2 hours. Kills fleas before they have the chance to lay eggs - thus breaking the flea life cycle. Effective up to 6 weeks! Advantage is for dogs over 7 weeks old.