Celebrex (Celecoxib) is a nonsteroidal anti-inflammatory drug (NSAID) that is used to treat arthritis, pain, menstrual cramps, and colonic polyps. Prostaglandins are chemicals that are important contributors to the inflammation of arthritis that causes the pain, fever, swelling and tenderness. Celecoxib blocks the enzyme that makes prostaglandins (cyclooxygenase 2), resulting in lower concentrations of prostaglandins. As a consequence, inflammation and its accompanying pain, fever, swelling and tenderness are reduced. Celecoxib differs from other NSAIDs in that it causes less inflammation and ulceration of the stomach and intestine (at least with short-term treatment) and does not interfere with the clotting of blood.