FDA authorizes first generic drug to combat NWS myiasis in pets

Earlier today the FDA announced it has issued an Emergency Use Authorization (EUA) for generic Nitenpyram Tablets for the treatment of New World screwworm (NWS) myiasis in dogs, cats, puppies, and kittens that weigh at least 2 lb and are at least 4 weeks old. The FDA also shared that it is the first generic animal drug to receive authorization for use against NWS.¹

“Generic animal drugs build resilience in our domestic supply chain and play a critical role in expanding the toolkit of US veterinary drugs for New World screwworm,” said Timothy Schell, PhD, director of the FDA’s Center for Veterinary Medicine, in an organizational release.¹ “By authorizing this generic treatment, FDA is reinforcing our commitment to providing timely, affordable options to safeguard animal health for American pet owners.”

The agency concluded the Nitenpyram Tablets may be effective in treating NWS myiasis in certain dogs, cats, puppies, and kittens based on the totality of scientific evidence available as well as the known and potential benefits of the product outweigh the known and potential risks.¹ For those using these tablets to treat NWS, veterinary professionals may also need to remove any larvae that remain, dead or alive. The FDA suggests the removal be done by someone trained in veterinary medicine to help minimize the risk of infection or further damage tissue. As for pet owners, they should contact and consult with a veterinarian about appropriate wound care, and how they can help minimize the risk of reinfestation.

RELATED: FDA-authorized and approved animal drugs for New World screwworm²

Once the NWS flies lay their eggs on open wounds or mucous membranes of mammals, within hours the larvae will hatch and burrow into the animals’ flesh. Nitenpyram then works quickly to kill most NWS larvae within hours of receiving the first dose. Pet owners should administer a second dose of the medication 6 hours after the first. Nitenpyram Tablets do not prevent NWS myiasis or protect against reinfestation because its effects are short-acting.

The Nitenpyram Tablets are available over the counter and come in 2 sizes: 1.4 and 57 mg. Each dose is based on the pet’s weight and should not be administered to pets that are less than 2 pounds. For safety information related to redosing, use in pregnant or nursing dogs and cats, and together with other products, the FDA advises referring to the package insert.

“The FDA has spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the US,” said Acting FDA Commissioner Kyle Diamantas. “As of today, under the Trump administration’s decisive leadership, the FDA has issued ten EUAs and three conditional approvals for drugs to combat this threat, and this count will continue to grow as we receive more animal drug submissions and unleash American regulatory speed.”

dvm360 is actively tracking NWS cases, FDA treatment authorizations, industry response, and other developments. Click here for live updates and expert commentary.³

References

1. FDA Issues Emergency Use Authorization for Generic Over-the-Counter Drug to Treat New World Screwworm in Dogs and Cats. News release. US Food and Drug Administration. June 11, 2026. Accessed June 11, 2026.
2. Bautista-Alejandre A. FDA-authorized and approved animal drugs for New World screwworm. dvm360. June 8, 2026. Accessed June 11, 2026. https://www.dvm360.com/view/fda-authorized-and-approved-animal-drugs-for-new-world-screwworm
3. Bautista-Alejandre A, Mazzolini C. New World screwworm updates: The latest on government, industry response, new cases. dvm360. June 4, 2026. Updated June 8, 2026. Accessed June 11, 2026. https://www.dvm360.com/view/new-world-screwworm-updates-the-latest-on-government-industry-response