Once I started using the drops you put on their backs I never had problems with fleas again. I used to mess around with all sorts of sprays, shampoos and flea powders and flea collars and all sorts of crap that just plain old didn't work. But the drops on the back work- advantage, frontline, advocate, etc. Just gotta remember not to put them on straight after you wash the dog, the dog has to get it's natural oils up for it to work.