I've told the story here about adopting the cat I'd been taking care of at my work place. I had dosed her with Frontline a week before I brought her in but my cats had always been inside and never been treated for fleas. So, of course, we got fleas. I put them all on Frontline as soon as I realized, about three months ago now. Unfortunately, it's not working at all for my 22 pound male, Will. On top of that, he is allergic and has scratched and chewed several spots. I tried using a flea comb on him but I was afraid I was hurting him. I got some Capstar and have been giving it to him when I've seen evidence of fleas (about once a week), I gave him a pill this morning. It's a week until they are due for another dose. I bought some Advantage for all of them. Despite my constant efforts at treating the house and bedding, this week I've noticed that the two females have fleas again. So is it too soon to give them the Advantage or should I wait until next week? I feel so bad for Will. I think it's psychologically affecting him. Any itch and he starts furiously licking and growling, even if it's not a flea. I'm really hoping that the Advantage for large cats will help him. Any advice will be much appreciated.