Although I have not had any personal bad experiences with the Hartz flea drops, after seeing this site and all the testimonies, I will never use this product again. I had used the Hartz flea drops in the past, and I thank God everyday that there were no adverse reactions at the time. As I’m sure that are a few people out there that have used this product without an adverse reaction. And those of us who have should be very thankful that our precious fur babies are ok. I think I would much rather see a cat or dog have fleas than to take a chance on using an OTC product.