Celebrex relieves pain, and inflammation due to swelling. It treats pain, swelling and stiffness due to arthritis. A non-steroidal anti-inflammatory drug (NSAID), Celebrex works by blocking the enzyme in the body that makes prostaglandins. (Reducing prostaglandins, helps minimize pain and swelling.) Celebrex is taken by mouth, once or twice as directed by a physician. When Celebrex is taken with food, it decreases the chance of an upset stomach. The dose requirements are based on a person’s medical condition and a response to therapy. An upset stomach, gas diarrhea, and nausea are the symptoms that may occur with Celebrex use.