Revolution works very well, and you can get kitten (8 weeks) doses for it. Most other meds have to wait until 12 weeks. Last year we had an earmite outbreak so we went through a lot of kitten revolution.

Watch out for any topicals which contain a compound called "pyrethrin". That's the same stuff that's in Raid and is bad for cats that come in contact with it. Most OTC flea topicals and flea collars have this compound in it.