I have used Frontline Plus for cats for years and it has worked well. Everytime I go to my vet, they ask whether I am using flea protection, of course I tell them yes. The last time I was aked that question (January 2014) I got mad and sent all of the product back to Foster & Smith. They are replacing it with Advantage. I have been told that when Frontline lost their patent, that something went wrong. I know what went wrong, it does not work as well. This has been going on for months now and I will never use it again. My neighbor says she stopped using Frontline Plus as well for the same reason. There was also a consumer report on my local television about flea protection not working but I don't remember if they mentioned the brand. They showed you how to apply it properly. I had been doing that once per month. I understand that Frontline Plus for Dogs is good for ticks but do not buy it for cats or you are wasting your money.