Vioxx (rofecoxib) is a prescription COX2 inhibitor nonsteroidal antiinflammatory drug (NSAID). Vioxx works by inhibiting the COX2 form of the COX enzyme to block production of prostaglandins. Prostaglandins are hormonelike substances that contribute to the symptoms of pain, fever and inflammation. Vioxx was used to treat arthritis, acute pain in adults, and painful menstrual cycles. Vioxx was approved by FDA in May 1999 for the relief of the signs and symptoms of osteoarthritis, for the management of acute pain in adults, and for the treatment of menstrual symptoms. Vioxx was later approved for the relief of the signs and symptoms of rheumatoid arthritis in adults and children. It comes as a tablet and a liquid that is usually taken once a day orally with or without food.