With an added IGR (Insect Growth Regulator), Advantage® II kills fleas at all life stages, even the eggs and larvae. The waterproof formula comprehensively targets flea infestations to interrupt the flea life cycle at multiple stages. Killing all fleas within 12 hours and provides protection against reinfesting fleas for up to 1 month. Plus, fleas don't have to bite to die - they are killed through topical absorption. Prevents fleas on treated animals from reinfesting your home, making fleas easier to manage. The canine formula also kills lice for added parasite protection. With quality protection against fleas and ticks, it also helps reduce the risk of secondary problems such as flea allergy dermatitis or tapeworms. Sorry, these products cannot be shipped to Puerto Rico and Canada.