My cat Harry started having a seizure and began to hallucinate within six hours of applying the topical Hartz flea treatment for cats. I had to rush him to the vet as he was starting to become distressed while breathing and he couldn’t stand up or walk. He kept falling down. It was heartbreaking and scary to see him go through this ordeal. I do not recommend anyone use this product on their cat OR their dog. After informing a friend of what happened, she had told me that her dog had passed after applying the dog version of the Hartz topical flea treatment. This brand is dangerous and should be removed from the shelves completely. If your cat is showing any signs of distress after applying flea medication, promptly bathe them in dawn soap. This helps dilute the medication and prevent further absorption into the system, and get them to a vet right away for further treatment. My cat was administered fluids and given medication to help with the tremors. I am happy to report he has recovered but he almost didn’t make it once he began having respiratory issues. Pesky fleas can be an issue but please keep a close on your cat if you choose to use this product; but I advise against it!