we were trying to save money by buying hartz flea medicine at wal-mart instead of going to the vet for advantage. little did we know what would happen to our cats! we put it on them, and a few hours later they seemed fine, but the next morning they were both twitchy and acting wierd. they were hiding and trying to get the medicine off. we gave them both baths, and then i was going to look up the website to send hartz a letter and found out how many other people have had this experience! they seem fine now, they are both dry and taking a nap on the bed. their ears are still twitching a little, i don’t know if it is because of the medicine’s effects or because they don’t like the water, but as of now, it seems like they will be okay. we had a scare! and next time we are definitely going to the vet to get advantage again, which has worked before on these cats with no adverse effects.