We did not try the Hartz flea shampoo but decided on Seargeant’s flea and tick shampoo instead. Our kitten, Cuddles, was four months old at the time and the label clearly states that it’s ok to use on kittens over 12 weeks old. It also states that you should lather your pet and leave on for 4-5 minutes. Thank God we didn’t leave it in that long because he probably wouldn’t have been able to pull through. We used a small amount on his torso,lathered and rinsed it right off. He seemed ok that night but the next day was horrible. I came home from work to find him lying on the floor. He was breathing very rapidly, drooling, and crying. He tried to get up and walk but he had temporarily lost his sight and walked into the wall instead. We took him right to the vet who told us that he had suffered a seizure from the flea bath. They told us that they see about 200 cases a year from the Hartz and Seargeant’s brands. They also said that both companies are well aware of the problem but do nothing to stop it. None of us thought that little Cuddles would make it through the night, but thankfully he did. He was able to come home the next day. It took about a week before he felt good enough to start playing again though. Since then he has suffered another seizure, this time he lost his sight for 2 days. It has been about a month since the last seizure and he is finally doing good. The vet thinks it is all out of his system now and we are all hoping for the best. Just so you know, he did not injest any of the shampoo. It was absorbed through his skin during the bath. So please, all of you who read this, do not buy Seargeant’s flea products either. These companies do not care about our pets,to them it’s all about the money.