• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

Animal & Veterinary

  • Print
  • Share
  • E-mail

Caution Urged In Using Warbex

October 4, 1996

Warbex® is the tradename for the liquid form of the chemical famphur, regulated by FDA as an animal drug, which is designed to be applied topically to treat insect infestations. The product is approved by the FDA for use on beef cattle, dry cows, and replacement heifers to treat grubs and reduce lice infestation.

There have been reports of death of wild birds due to the deliberate misuse of Warbex®, and even in some cases when the product is used properly. Warbex® is being misused by soaking grain and other items in the liquid famphur. The contaminated grain or other products are then used as bait or as a delivery vehicle to poison birds, rodents, or predators. This practice introduces famphur into the wildlife food chain. Endangered species, as well as other predatory and scavenging birds, including eagles, hawks, owls, and buzzards, etc., have died as a result of eating these poisoned birds. An undetermined number of bald eagles and red-tailed hawks in Washington State have died after eating starlings that had been intentionally poisoned. Some of this illegal use may be occurring on dairy farms in other States. Birds have also died when Warbex® has been applied to the backs of cattle according to label directions. Some bird species perch on cattle backs and others pull cattle hair, and these birds may receive fatal exposures to famphur.

CVM views the misuse of this product as an unapproved use in violation of the Food, Drug, and Cosmetic Act and implementing regulations. There are discussions underway between the various Federal and State agencies involved to decide how best to sanction or control individuals who use the product in this illegal manner. The State of Washington Department of Agriculture has taken the unusual step of requiring registration of the animal drug as a pesticide under State law. A Pesticide Dealer License is now required for any outlet which distributes Warbex® in Washington.

CVM is working with Mallinckrodt Veterinary, Inc. and the U.S. Fish and Wildlife Service to educate the public about potential hazards to wildlife associated with Warbex® Pour-On 13.2%. Mallinckrodt is planning a public education campaign to try and discourage misuse of Warbex®. Their educational materials will also address the potential environmental problems from use of Warbex® according to the label and how to prevent them. Mallinckrodt will advise product users to promptly dispose of any poisoned birds in a manner that ensures that the carcasses are not available to other predatory and scavenging birds.


Contact FDA

240-276-9115 FAX
Issued by: FDA, Center for Veterinary Medicine

Communications Staff, HFV-12

7519 Standish Place

Rockville, MD 20855