The dog got fleas, so now the cat has fleas
FrontLine/FrontLine Plus have been very good to us over the years, so I put FrontLine Plus for Dogs 45-88 pounds on the dog. Since her tongue can apparently reach every part of her body

she licked it and drooled massive amounts for about 15 minutes. Next time I'll put a
cone on her to prevent ingestion

She's scratching a lot less anyway
I checked with Banfield and was told feline flea preparations like FrontLine Plus and Advantage II were safe on cats (including diabetics). The PetSmart Manager recommended FrontLine Plus, Cat MD (same ingredients as FrontLine Plus), and Advantage II as being the most effective of what they had on-hand, and said Sentry didn't seem to work as well. Since Advantage II had caused a chemically smell on a previous dog in the past, that was not an option for the cat. I used FrontLine Plus on the cat. He did not lick it and neither the application nor the chemicals bothered him. He hasn't been scratching very much, but I know the fleas/larvae/eggs will be gone/dead quickly
I also flea bombed the car (definitely
not IAW with the directions on the can 
) and will flea bomb the apartment when I move out

I used the Advantage flea bomb, but I'll be looking for something else to keep on-hand after we move, as I don't like the smell. At least it didn't leave a sticky residue

I remember a flea bomb from years ago that actually smelled good... kind of lime-y... maybe it had liomene in it?
I've read several articles lately warning not to use Hartz, Top Spot, etc. flea preparations as they are hazardous/lethal to pets. Past experience has taught me Adams is about the harshest/nastiest thing out there, but it worked when absolutely nothing else did (I did not have access to Sevin Dust at that moment, which is an old product, very effective, very messy, but hazardous/deadly to endangered butterflies--I no longer use it). Adams left an absolutely horrible chemical smell on the dog that got all over everything and persisted for over a month and made
me sick. Even the dog didn't like how she smelled. But the FrontLine-resistant fleas that she got at a truck stop were
DEAD! DEAD! DEAD! Ha ha ha!

There are some botanical/herbal/organic products out there, but I don't know how well they work. At least one is only to repel and does not kill fleas.
Important: some flea preparations that are considered safe for cats and dogs are hazardous/deadly/tetragenic/etc. nursing/pregnant/unborn cats and dogs.