My wife purchased Hartz kitten (10lbs or under) flea drops from Walmart. I used it on Chaz last Sunday around 2:00pm. Later that night I went to check on him before bed and he was hiding. Chaz is the most out-going cat we’ve ever owned. Loves attention, plays all the time. Runs to you evertime you’re around. But that Sunday night he was hiding from me. Once I found him I could immediately tell something was wrong. His eyes twitched and he couldn’t walk without shaking his legs and feet. All he wanted to do was find a place to hide. I knew it had to be the flea drops. I immediately washed him and tried to get him to drink something. He turned his nose up to water, but did drink some milk and that appeared to help some. But still all he wanted to do was hide / sleep. The next morning all was well. He was back to normal. I still can’t believe they can sell this stuff over the counter.