The U.S. Food and Drug Administration issued an Emergency Use Authorization (EUA) authorizing Capstar (nitenpyram) tablets and revising the EUA for generic Nitenpyram Tablets to permit both prevention and treatment of New World screwworm (NWS) infestations (myiasis) in dogs, puppies, cats, and kittens that meet specified age and weight criteria. Nitenpyram Tablets had been previously authorized in June 2026 for treatment only; the current action expands authorized use to include prevention.
The FDA concluded, based on the totality of available scientific evidence, that it is reasonable to believe these products may be effective for prevention and treatment of NWS myiasis in certain animals when used as authorized, and that the known and potential benefits outweigh known and potential risks.
The EUAs cover two commercially available, over-the-counter products: Capstar and Nitenpyram Tablets. Both products are available in two tablet sizes: 11.4 mg and 57 mg. Dosage instructions are based on the animal’s weight. The EUA materials, including Fact Sheets, FOI Summaries, and Letters of Authorization, are posted by the FDA on its New World Screwworm emergency information webpage.
The authorization applies to dogs, puppies, cats, and kittens that weigh at least two pounds and are at least four weeks old. The EUA explicitly advises against administering these products to pets weighing less than two pounds or younger than four weeks of age.
The FDA notes that most dogs and cats in the United States are at low risk of exposure because confirmed NWS cases are confined to a limited geographic region. However, animals that live in, travel to, or return from areas where NWS infestations have been identified by state or federal animal health officials, as well as certain countries south of the U.S. border, should be monitored closely for signs of infestation.
The FDA’s determination follows review of the totality of scientific evidence available to the agency. The conclusion was that the balance of benefits and risks supports authorization of Capstar and Nitenpyram Tablets for prevention and treatment of NWS myiasis in specified animals when used as directed under the EUA.
Timothy Schell, Ph.D., director of the FDA’s Center for Veterinary Medicine, stated that although multiple products have been authorized or conditionally approved for treatment of NWS, none had been authorized for prevention until this EUA, and that the action addresses a previously unmet need for pet owners and veterinarians.
Capstar and Nitenpyram Tablets are available over the counter in 11.4 mg and 57 mg tablets. Dosage is determined by the pet’s weight. The EUA materials provide specific dosing and administration instructions; pet owners and veterinarians should consult the relevant EUA Fact Sheet before use.
Do not administer these products to animals that are under two pounds in weight or younger than four weeks of age. For full, product-specific directions and any additional use limitations, refer to the EUA Fact Sheets and related documents posted by the FDA.
Owners and veterinarians should watch for clinical signs of NWS myiasis, such as visible maggots or foul odors emanating from wounds or body openings including eyes, ears, nose, or mouth. The FDA advises seeking immediate veterinary care for animals that are infested.
The EUA states that the known and potential benefits of Capstar and Nitenpyram Tablets outweigh known and potential risks when used as authorized. For detailed safety information, contraindications, and adverse event guidance, the EUA Fact Sheets and FOI Summaries should be consulted.
These EUAs will remain in effect until they are revoked by the FDA or until the Secretary of Health and Human Services terminates the declaration that the potential public health emergency presented by NWS justifies emergency authorization of animal drugs for this condition. The source document references the HHS declaration that underpinned the emergency authorizations.
Capstar is sponsored by Sergeant’s Pet Care Products LLC of Omaha, Nebraska. Nitenpyram Tablets are sponsored by Felix Pharmaceuticals Pvt. Ltd., based in Ireland. Both products are available over the counter in the specified tablet sizes.
For up-to-date information on U.S. detections of New World screwworm, the FDA directs readers to the U.S. Department of Agriculture’s Confirmed Detections of New World Screwworm dashboard. All EUA product Fact Sheets, FOI Summaries, and Letters of Authorization are posted on the FDA’s New World Screwworm emergency information webpage.
Related links and resources were provided in the source announcement for veterinarians, pet owners, and public health officials to access detailed product information and the latest case updates. The FDA press release is current as of 09/03/2026.