When I noticed just a few fleas on my cat, I went out to the store to find something to get rid of them. Unfortunately, I decided on the Harts 3-in-1 flea drops. I thought these would work well since they are supposedly similar to the Advantage line, etc, that you can buy from your vet. I followed the directions on the box and applied the drops on the back of my cat’s neck. The reaction my cat had happened quickly. Even though it was on the back of his neck he was still able to reach it and lick much of it off. His personally changed drastically. He became very lethargic and slept constantly. Fearing a bad reaction, I quickly washed the product off of him. For the next day, he would shake on and off and sleep most of the time, not at all his normal personality. Today, two days after applying it, he is beginning to act more normal, but I have noticed he is having some trouble with balance. I only hope that he can completely recover from this. I feel terrible that I put my cat in harm’s way over this. I hope that other cat owners see this website and do not make the same mistake. This product should not be on the shelves!