Manufacturers could do us all a favor and stop calling anything a flea shampoo. While an shampoo that contains an insecticide may kill fleas on your pet if it comes in contact with them, this would only be of benefit if it were the first and only flea on your pet. Shampoos are only effective while you bath your pet, there is no lastiing effect after rinsing. At least a product such as Capstar will kill all the fleas on your pet when you give it. More information is available in drpups discussion of fleas.