Advantage For Dogs Advantage is a once a month easy to apply flea prevention. Advantage starts working within minutes. The fleas are not required to bite to receive the lethal dose. It kills adult fleas and larvae on the Dog and in surrounding areas. It is safe for use on pregnant & lactating animals. It is not necessary to treat unweaned Puppies as the mothers treatment will protect the litter while in contact. Advantage is available in 4 & 6 packs.