No, products like Frontline plus are absorbed into the skin and spread throughout the body of the animal and secreted in the oil glands. The flea only has to have contact with the oil in their coats for it to be effective.

Depends which topical you are using. Some are strictly surface products, such as Frontline (Fipronil) and Advantage (Midocloprid) and fleas only need to contact these products to die. But other products you put on topically get absorbed into the blood stream and make it toxic to the fleas (like the Selamectin in Revolution, or the other crappy products in the super cheap over the counter products). Most of those latter products are not too effective, and somewhat dangerous for cats, so I would stay clear of those. Not all cats with dermatitis have current flea allergies by the way... many cats are allergic to other things and all the flea products in the world may not make a difference. Does you cat actually have fleas?

I surely agree that the OTC products are not all that effective and can be dangerous, especially to cats. Thanks for the clarification that the mode of action does depend on the product. But fleas biting the animal does not need to occur. Did you intend to imply revolution was dangerous or crappy, or did I just read it that way. It's pretty expensive compared to the other 'spot' flea products, but that is what I chose for my cats because I found it to be very effective and also it controls more parasites, especially ear mites and I have a cat who has them chronically and they resist any other treatment but Revolution controls it for him. I just really think that product is worth the price.

NO, I did not mean that at all, sorry. Revolution is a great product... it is most of the other absorbed products that I would shy away from (anything OTC). Just my poor wording of that sentence.