What do I give Chewy against fleas?

Both my cat AND my hamster are badly infested with fleas (I'm guessing my cat got them from next doors dog who constantly has fleas and is never cured, and the hamster got them from the cat). I havn't found any on Chewy, but he probably has some because he does scratch himself alot, I probably just can't find them because he is dark brown and moulting.
I have never had a bunny with fleas, so could anyone tell me what I have to use to get rid of them? Is it ok if I use the same product as for the cat? Also, I don't know how to deal with the hamster's fleas either...

I have used spot-on that I got from the vet called Advantage. You can buy it on-line. Just make sure you buy the one for rabbits because it comes in different strengths.

http://www.animaldrugsonline.co.uk/pricelist.pdf

My first bun Holly arrived with a flea and was soon absolutely heaving with them. She was cleared up pretty soon and didn't get them again, but then the house she came from had cats and we don't so she didn't seem to pick any more up after she had been treated.

You part the fur and pop it onto their skin. Make sure it isn't too far down their back where they can twist round and groom the spot. I put it on about an inch beyond their ears.

Defo don't buy an off the shelf 'johnsons' type make one. get advantage online or go to your vets and they will sell you good ones for hamster/rabbit and cat. be careful the rabbit doesn't get any cat de-flea-er on as it can make them really ill. Fleas carry worms so you will need to worm your cat as well if you haven't already (again vet strength type not supermarket shelf 'wormer').