Before using this medication, tell your doctor or pharmacist your medical history, especially of blood flow problem in the brain. Fluconazole increases the concentration of Celecoxib in the liver. Celecoxib is used to reduce pain and inflammation in osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis. Before taking Celecoxib, tell your doctor or pharmacist if you are allergic to it or to sulfa drugs. Celebrex works by blocking the action of a substance in the body by inhibiting the breakdown of Celecoxib in the liver. Celecoxib should only be used in pregnant women when the benefits outweigh the potential risk to the fetus.