Rofecoxib or Vioxx is a COX-2 specific inhibitor. Cyclo oxygenase compounds are found throughout the body - for example, in the nervous system and stomach. COX-2 is a type of cyclo oxygenase that produces prostaglandins that cause pain and inflammation. COX-1 is a type of cyclo oxygenase that is found in the stomach that helps protect the stomach lining. Thus, being specific for COX-2, Rofecoxib or Vioxx reduces pain and inflammation with little stomach irritation