I use it for my cat to help prevent fleas. However he tends to run out and probably collect more adult fleas which I'm interested in killing/preventing infestation immediately. Keep in mind this medicine only kills flea eggs and does not work as immediately as the topical flea medicines. I would prefer to mix this stuff into his food and not have to deal with wrangling my cat down to apply cold topical on his bare skin but in the end, I think I have to go back to the topical. :(