Advantage flea treatment - warning

I've just had a scary half-hour with Thom, thought I'd write about it as a warning for other cat owners. I put some Advantage flea treatment on Thom, thought I was doing a good thing as he's got a lot of scratching going on. Well, the first smell of it had him foaming at the mouth and darting around the room to get away from it. I plunked him in the laundry tub and washed him down with warm water and a mild lavender soap straight away, and he's now having a good wash in the sunshine on the couch. Scared the hell out of both of us, poor Thom-tom. I've never seen a reaction like that before; I've never used Advantage before, always used Frontline and had no problems, but this is the first time I've dosed Thomas myself - the SPCA and the vet did it before. The Advantage does have a very strong chemical smell, unlike Frontline. So I'll get Thom flea'd with vet approved stuff from now on.