Fast-acting Advantix eliminates 98-100% of all fleas on dogs within 12 hours of one quick and easy application. Effective formula contains Imidacloprid to kill fleas on contact before they lay eggs and permethrin to kill and repel ticks and mosquitoes. Waterproof Advantix continues working even after bathing or swimming to prevent reinfestations for up to four weeks. Spot-on treatment is easy to use; simply part hair on dog’s back between shoulders and apply to skin. Safe for dogs and puppies over 7 weeks old. Not for use on cats.