Advantage, applied once each month, kills fleas on your pet fast and breaks the flea life cycle Advantage is easy to apply - you simply squeeze the pre-measured dose onto the back of your cat's neck. Advantage then spreads over your cat, remaining in the oily layer of the skin, where it is effective against fleas all month long. Best of all, fleas don't have to bite your cat to be affected, so with Advantage your pet suffers less of those painful flea bites.