Weve been using it on gibson for almost a year. When we first decided to try it he was "infested" with fleas and flea eggs. He was always itching and had scabs all over his neck. It didnt matter how many times we cleaned him with the flea comb (he never went out side) they kept coming back. So we decided to try it. By the time his next vet visit a month later he only had a couple on the comb and no flea eggs. We used it one more month and they were all gone until the following summer. Then we just restarted the process. And he has been flea free since. And he is a much happier kitty for it.