While flea and tick preventatives are essential for protecting pets from parasites and the diseases they carry, some products have been associated with adverse effects. For example, certain medications, particularly those in the isoxazoline class, have been linked to neurological adverse events in dogs and cats.
Click on the link for more information:
https://www.fda.gov/animal-veterinary/animal-health-literacy/fact-sheet-pet-owners-and-veterinarians-about-potential-adverse-events-associated-isoxazoline-flea
North America