I have 3 indoor cats who somehow managed to get fleas. I looked online to see how much the vet recommended flea medicine was and found that it was about 45 dollars for 3 months, thus to do all my cats once it would be 45 dollars. I decided instead to by the Hartz 4 in 1 flea drops for cats for about 10 dollars. BIG mistake. I went home and put it on my 2 year old cat. At first he seemed okay but the next monring he wasn’t himself at all. He hid downstairs and refused to come up and be around us (very unusual considering my cat loves people, especially me). Worried i went to work and had my husband check on the cat throughout the day. By the time i got home I knew something was wrong. He was laying in a basket of towles in the basement shaking. I rushed him to our local vet who told us apparently this is quite common with Hartz products. I was outraged when I found out. Thankfully he is okay… The vet gave him some muscle relaxants to stop the shaking and we went home and gave him a bath in Dawn. Still it was a very scary experience! After reading other stories online I feel lucky it wasn’t worse. i will NEVER EVER use another Hartz product again and I am going to tell EVERYONE I know about this! Its horrible that this happens all the time to cats yet the product is still being sold!!