Advantage Teal kills fleas on dogs fast. Advantage kills 98% of fleas within 12 hours and continues to work for up to one month per application. It also breaks the flea life cycle by killing flea larvae. Advantage can be used on puppies as young as 7 weeks old. Also, it is safe for dogs that are pregnant or nursing. Advantage is water-resistant, so it kills fleas even after shampooing and exposure to rain. Advantage is applied between the shoulder blades on dogs. Effective Flea Control . . . No Prescription Required!Guaranteed US EPA approved. Contains imidacloprid, the fastest flea preventive, which works within 12 hours Long-lasting Over-The-Counter formula keeps working for up to 4 weeks Easy-squeeze tube for easy application. Water-resistant formula stays strong through baths and rain