Advantage is a fast-acting, water resistant, easy to apply monthly spot-on that kills fleas on contact, so there's no need for them to bite! Reinfesting fleas stop biting in 3-5 minutes and are killed within 1 hour. Larval flea stages are killed in the cat's surroundings, and it reduces the incidence of flea allergy dermatitis. Safe to use on kittens from birth & on pregnant and lactating cats. Treatment of the mother protects unweaned kittens.