FDA Issues Emergency Use Authorization for New World Screwworm Drug for Dogs
The U.S. Food and Drug Administration today issued an Emergency Use Authorization (EUA) for Credelio (lotilaner) chewable tablets, concluding that, based on the scientific evidence available, it is reasonable to believe that Credelio may be effective in treating New World screwworm (NWS) infestations in dogs and puppies and the known and potential benefits of the product outweigh its known and potential risks. This is the first time ever that the FDA has issued an EUA for an animal drug.
“The FDA acted swiftly to make a screwworm treatment available for dogs in the U.S.,” said FDA Commissioner Marty Makary, M.D., M.P.H. “When it comes to emerging animal health threats, we need to be proactive, not reactive.”
“The FDA is using EUAs to bolster our nation’s preparedness for NWS,” said Timothy Schell, Ph.D., director of the FDA’s Center for Veterinary Medicine. “We are working expeditiously to review additional product-specific NWS EUA requests for animals that could be affected by NWS, including livestock, companion animals and wildlife.”
While the majority of dogs in America are at low risk of NWS due to their geographic location, dogs near the U.S.-Mexico border and dogs that have traveled to countries with active NWS cases are more likely to be exposed to NWS.
The risk to human health from NWS in the United States remains very low. Although eradicated from North America and Central America decades ago, NWS has progressed north since 2022. The parasite poses an emerging threat to livestock and food security, with potential impacts on both national security and animal health. NWS infests warm-blooded animals, including livestock, pets, wildlife, and, in rare cases, humans, causing severe tissue damage and sometimes death.
In August 2025, the Secretary of Health and Human Services determined that NWS presents a significant potential for a public health emergency and gave FDA the ability to issue EUAs for animal drugs to prevent or treat NWS. This EUA will be effective until it is revoked or the HHS Secretary terminates the declaration.
The FDA originally approved Credelio in 2018 for flea and tick-related indications in dogs and puppies.
Lotilaner, the active ingredient in Credelio, belongs to a class of antiparasitic drugs called isoxazolines. Although isoxazoline products are commonly used and safe for most dogs, the products have been associated with neurologic adverse reactions, including muscle tremors, ataxia, and seizures. Pet owners should consult with a veterinarian to determine whether Credelio is appropriate for their pet.
Credelio is available only by prescription from a licensed veterinarian because professional expertise is required to monitor for and respond to potential adverse reactions. Detailed product information for veterinary practitioners can be found in the Fact Sheet for Veterinarians: Emergency Use Authorization of Credelio (lotilaner).
