The FDA is warning pet parents and veterinarians about potential neurological side effects linked to certain flea and tick products. Find out the details.

FDA Warns Neurologic Risks With Certain Flea & Tick Prevention Products


Dogs and cats treated with certain flea and tick prevention products may be at an increased risk for neurologic events, according to the U.S. Food and Drug Administration (FDA). 

This week, the FDA released a warning to pet parents and veterinarians saying pets treated with drugs in the isoxazoline class may run the risk of muscle tremors, ataxia, and seizures. Some of the specific product names mentioned in the FDA’s release include Bravecto, NexgardSimparica, and Credelio.

According to the official notice:

“Since these products have obtained their respective FDA approvals, data received by the agency as part of its routine post-marketing activities indicates that some animals receiving Bravecto, Nexgard or Simparica have experienced adverse events such as muscle tremors, ataxia, and seizures. Another product in this class, Credelio, recently received FDA approval. These products are approved for the treatment and prevention of flea infestations, and the treatment and control of tick infestations.”

Still, the agency says it carefully reviewed studies on Bravecto, Credelio, Nexgard, and Simparica prior to approval and states “these products continue to be safe and effective for the majority of animals.”

Moving Forward

Now FDA officials are working with manufacturers of isoxazoline products to include new label information to highlight neurologic events.

“The agency is asking the manufacturers to make the changes to the product labeling in order to provide veterinarians and pet owners with the information they need to make treatment decisions for each pet on an individual basis. Veterinarians should use their specialized training to review their patients’ medical histories and determine, in consultation with pet owners, whether a product in the isoxazoline class is appropriate for the pet.”

Notice A Problem With Your Pet?

To report suspected adverse drug events for these products, the FDA says you can contact the appropriate manufacturers at the following phone numbers:

  • Merck Animal Health (Bravecto): 800-224-5318
  • Elanco Animal Health (Credelio): 888-545-5973
  • Merial (Nexgard): 888-637-4251
  • Zoetis (Simparica): 888-963-8471