Just wanted to share my Hartz horror story. I thought I would save a little money and buy Hartz flea medicine instead of Advantage. I actually was delighted to see they now had the cheaper flea medicine for cats = they had it out for dogs for years. I put the tube on my 8 year old cat (9 lbs.) in the evening. The next day when I came home from work there were piles of her hair everywhere. It was very strange. At first I thought it couldnt be her hair & wondered what it could be. But then I went & pulled on her hair & it gave way. I called Hartz & they told me I needed to bathe the cat 3 times = once with dish detergent & twice with a mild shampoo. (Which is nearly impossible = especially by yourself.) They said she was obviously having an allergic reaction to the medicine. They also sent me a refund for the purchase price of the medicine.