Either of the topical flea applications will not prevent fleas from getting on or biting your cats. What is does is kills the fleas after they bite. That doesn't get rid of what is already in your house. You should use a bomb every two weeks in your home until you have the infestation undercontrol. The bomb does not kill the flea in the pupa (sp?) stage. That stage has about a 2 week life cycle, thus the bombing every two weeks.

The labeling on both products that you mentioned states that you can bath the animals and it won't wash off the product. I would however watch my cats closely if you decide to bath them with another flea control product. Some cats can be overly sensitive to chemicals, especially if they are an aged kitty. If you have an older cat or one that has shown a sensitivity before, I would call your vet and ask them if they have any flea products for older or sensitive cats.

Good luck. A flea investation is about the harderst thing to combat.