Fenclofenac (Flenac) is a non-steroidal anti-inflammatory drug previously used in rheumatism. Fenclofenac was shown to possess anti-inflammatory, antinociceptive and antipyretic properties. Flenac is an acetic acid nonsteroidal antiinflammatory drug (NSAID) with analgesic and antipyretic properties. Flenac is used to treat pain, dysmenorrhea, ocular inflammation, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and actinic keratosis. It has mild immunosuppressive effects and may displace thyroid hormone from its binding protein. The antiinflammatory effects of Flenac are believed to be due to inhibition of both leukocyte migration and the enzyme cylooxygenase (COX-1 and COX-2), leading to the peripheral inhibition of prostaglandin synthesis. As prostaglandins sensitize pain receptors, inhibition of their synthesis is responsible for the analgesic effects of Flenac. Antipyretic effects may be due to action on the hypothalamus, resulting in peripheral dilation, increased cutaneous blood flow, and subsequent heat dissipation. Fenclofenac, despite passing animal toxicity tests in 10 animal species (mice, rats, guinea pigs, ferrets, rabbits, cats, dogs, pigs, horses, and monkeys), produced severe liver toxicity in humans. Due to its side effects it was withdrawn from the UK in 1984.