I've known about this problem for quite some time and even posted something about it in cat health a long time ago. I once bought Hartz flea drops for my cats thinking that I would save money. I only used it once and luckily none of them had any reactions. When I learned how it was unsafe, I threw the rest away.

Now I'll only buy products that are veterinary approved and I've been using the large dog advantage and measuring the correct doseage for my cats for years without any problems. My vet was the one who told me that it was safe to do so because it's made out of the some stuff that the cat advantage is made from.

The public needs to be warned and more educated about using over the counter flea products. I still see them at stores all of the time.