Flunixin is a nonsteroidal anti-inflammatory drug (NSAID), analgesic, and antipyretic used in horses, cattle and pigs.

In the United States, it is regulated by the U.S. Food and Drug Administration (FDA), and may only be lawfully distributed by order of a licensed veterinarian.

[12] However, drug recycling from bedding contamination by treated horses has been shown to potentially increase the clearance time.

Administration of phenylbutazone to a horse also receiving flunixin has been shown to increase the risk of toxicity without improving analgesia.

[19] Interestingly, when given subcutaneously to goats in that study, tissue injury, such as seen in horses with intramuscular administration, was not observed.