Advice on Flea Treatments Please

[CatGirl]

I wonder if your cat does what one of mine does?She scratches the back of her neck,where the Frontline is,then cleans her claws with her teeth?

[Dawn F]

one of mine goes a bit hyper but only for an hour or so soI put up with it but do keep meaning to try stronghold

[sharonbetty]

I have two cats and have been using Frontline. Not regularly unfortunately and am now battling a flea infestation 
Have to be more vigilant in future.  One cat is fine wtih Frontline - doesn't have any reaction but the other one does have nervous reaction next day - lethargy or crazy behaviour.  Although the manufacturers say these are reversible, and they only last a day, I don't want to b e giving him anything every month that affects him like that.

I've spoken to the manufacturers who tell me that it is likely to be the alcohol carrier and not the active ingredent, fiprinil, which is causing the problems.  Has anyone looked into anything like this before and can give me any advice on what to use instead.  I appreciate your time.  Thank you.