Just found this website after telling my girlfriend about my horrible experience with Hartz, so this story is very dated (about 7 years). I rescued an abandoned kitten while at my mom’s house (we guessed he was about 6 weeks old). My mom already had a cat (about 1-2 years old) and really didn’t want another one & I couldn’t have animals where I was living. But this little guy was just too adorable. So the deal was, mom adopts if I get him all his shots, get him fixed & successfully handle the intro between him (Smokey) and her (Kitten…I know, real original name, whole other story). Successfully handled all that & couple months later the two were like brother & sister. A brother & sister going through puberty, who didn’t like each other, argued about who mom loved the most, but agreed to behave during meals & at bedtime. Anyway, I was picking up a bunch of stuff at either Petco or PetSmart to help my mom with cost when I saw the Hartz flea & tic stuff. I remembered growing up how my mom used it on our cat & dog. She got it from the vet, so I ignorantly thought, “Oh, that stuff used to only be available from the vet, but that was years ago & they now must hav a less potent version for over-the-counter use.” I get to the house & tell my mom that I picked up stuff (the cat version) to help with fleas like when I was a kid. Didn’t realize how important it is to consult your vet on almost everything these days. I put on the first dose & then told my mom to follow up per the directions. I applied to both cats & stayed to hav dinner. A few hours later, Kitten starts twitching. First one of her ears, then one of her front legs. Smokey, no reaction. We wait a little bit & it’s not getting better, but worse. I’m starting to freak out (on the inside) thinking, “Oh no, I just killed my mom’s cat.” I go online & find horror stories about this stuff. Into the bath Kitten goes, that was fun. What’s the best way to hold a cat? Where do u put the drops? Right, same for both…the neck. Got as much off as I could, while dodging flying poop & being clawed to death. She seemed a little better but not much. Back online I went. Some post recommended baby Benadryl in liquid form with an eye dropper. So I ran to CVS & got it. This really helped and crisis averted. It took her awhile but she seems to hav fully healed physically. Mentally, the cat was traumatized & has seemed a little off ever since. And she attacks me to this day, whenever I visit. Freaked me out & I tell everyone not to buy Hartz & consult their vet. We were lucky.