I almost lost one of my cats to Hartz flea medication, but it was the drops, not the shampoo. I don't think the shampoo is as bad, but I'm not sure. I just know it almost cost me my orange boy's life as all his organs started shutting down. He live through it and is now fine, four years later. It cost me about $2,000, though. I hope all of your kitties stay fine. I now use the flea meds from the vet. They are so much better than anything Hartz puts out.