I'd ask the vet before I'd use any medds, and I would NEVER USE the over the counter flea meds (Hartz etc...).

My first cat when I moved out had "a flea" on her (was told this by the shelter in 1994), and I bought this foam in flea stuff from Hartz or something like that. OMG... she got soooooooo sick!! You weren't supposed wash it out, and from her bathing herself, she ingested it when she was grooming, and she ended up so dehydrated and I had to take her to the ER. She was still infested with fleas and had to be IVd with fluids. It was horrible And she was a grown cat, so definitely be careful of what you do, and check with the vet first.

I know the kitten Revolution is MADE for kittens, but I'm not sure how old they have to be for it to be safe for them.