Etoricoxib belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). Etoricoxib eases pain and swelling (inflammation) in conditions like osteoarthritis, rheumatoid arthritis and ankylosing spondylitis, and it may also be used for short periods of time in gout. Etoricoxib works by blocking the effect of a natural chemical called cyclo-oxygenase-2 (COX-2) enzyme. This enzyme helps to make other chemicals, called prostaglandins, in the body. Some prostaglandins are produced at sites of injury or damage, and cause pain and inflammation. By blocking the effect of COX-2 enzymes, fewer prostaglandins are produced, which means pain and inflammation are eased.