WASHINGTON, D.C. — The Food and Drug Administration authorized emergency use of Bimectin ivermectin injections to prevent New World screwworm infestations in certain cattle, expanding the number of available drugs as federal officials seek to protect U.S. livestock from the parasite.
The emergency use authorization covers administration within 24 hours of birth, during castration or when a wound appears, according to the FDA. Bimectin is available over the counter without a prescription.
The drug is not authorized for lactating dairy cows or calves intended for veal production. Producers must also observe a 35-day withdrawal period before treated cattle are slaughtered to prevent drug residues from entering the food supply.
Bimectin is a generic version of Ivomec, an ivermectin product the FDA authorized in February 2026 to prevent New World screwworm myiasis in cattle.
“By authorizing both generic and pioneer products, the Agency is ensuring producers aren’t dependent on a single manufacturer or product to protect their herds,” Timothy Schell, director of the FDA’s Center for Veterinary Medicine, stated.
New World screwworm myiasis occurs when screwworm larvae infest wounds or other openings in living animals. The federal government has been working to limit the agricultural threat posed by the parasite.
The FDA determined that available scientific evidence provides a reasonable basis to believe Bimectin may be effective in preventing screwworm myiasis in cattle under the authorized conditions and that its known and potential benefits outweigh its known and potential risks.
The agency had previously approved Bimectin injection for treatment and control of several cattle parasites. The emergency authorization applies only to the injectable formulation and does not cover other forms of the product.
Cattle producers are responsible for administering the drug according to its labeling and accompanying fact sheet, the FDA stated.
The authorization will remain effective unless the FDA revokes it or the Health and Human Services secretary terminates the declaration supporting emergency use of animal drugs against New World screwworm.
Bimectin is sponsored by Ireland-based Bimeda Animal Health Ltd.
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