COX-2 inhibitors is the short name for a class of medications called cyclooxygenase-2 inhibitors. These fairly new medications stop the pain-causing enzyme cyclooxygenase. They can be very effective in relieving pain and inflammation. Vioxx and Celebrex, two COX-2 drugs, have been shown to be more effective in treating osteoarthritis than more familiar nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen. And COX-2 inhibitors don't seem to cause the stomach upset of NSAIDs.