FDA expands screwworm emergency toolkit with topical spray EUA

Topical spray receives EUA for prevention and treatment of New World screwworm

The FDA on March 10, 2026, issued an Emergency Use Authorization for F10 Antiseptic Wound Spray with Insecticide, a topical product containing benzalkonium chloride, polyhexanide, and cypermethrin, for prevention and treatment of New World screwworm myiasis in cattle, horses, minor hoofstock species such as sheep and goats, wild and pet birds, and captive wild, exotic, and zoo mammals. The product is available over the counter, but it cannot be used in domestic dogs or cats, and its authorization comes with food-safety restrictions including a 30-day slaughter withdrawal for cattle, goats, and sheep, plus a 10-day milk discard period for treated cows, goats, and sheep. FDA said the spray is the first NWS-related authorization to extend beyond cattle, dogs, and cats, broadening the emergency toolkit as federal agencies try to keep the parasite from moving north from Mexico. That toolkit also now includes an OTC injectable ivermectin product, Ivomec, authorized for prevention of NWS in cattle when given within 24 hours of birth, at castration, or when a wound appears; it carries a 35-day slaughter withdrawal and cannot be used in lactating dairy cattle producing milk for human consumption or in veal calves. (fda.gov)

Why it matters: For veterinarians, especially those in border states, mixed-animal practice, wildlife, avian, and zoo medicine, the EUA fills a practical gap by giving clinicians and animal caretakers a legal option for species that previously had few or no specifically authorized NWS tools. FDA’s fact sheet also makes clear that the agency is leaning on indirect evidence, including prior indexed use for fly strike and wound care in minor species and biologic plausibility against related blowflies, rather than direct efficacy data against Cochliomyia hominivorax. That means case selection, wound management, follow-up, and client communication around limitations will matter, particularly for food-animal withdrawal compliance and for pet parents who may assume the product can be used across species. In cattle, the growing menu of emergency-use products also means producers may be weighing topical and injectable options, making parasite-management planning and medically necessary use important to help preserve effectiveness. (fda.gov)

What to watch: Watch for additional FDA authorizations, field-use data, and any expansion of federal response measures as USDA and partner agencies continue surveillance, movement controls, and sterile-fly releases aimed at containing the outbreak. FDA has already used emergency authority for multiple product types, including the new F10 spray and OTC Ivomec injectable for cattle, suggesting the response will continue to evolve as outbreak pressure and species needs change. (fda.gov)