I believe its 2 or 3 days and youre fine. my dad (vet) said once you bathe them twice after having applied the adavntage, no matter how long inbetween, it doesnt work anymore. plus advantage only really works for 3 weeks (even though they tell you its a monthly thing). so, depending on how often you bathe your pets and how bad a prob fleas are for you, you might want to use something like program instead, or better yet, in addition. program & advantage are good to use together since they both kill fleas differently- advantage (topical) kills the adults and program (oral) prevents the eggs/larve from developing. I dont know anything about any other flea treatments, but I think there are other treatments out there that kill both the eggs & adults in one. dont know how effective they are (or arent) though either.