Celebrex is used to treat short-term pain (acute pain) in adults. It is also used for the treatment of primary dysmenorrhea (painful menstruation). Celebrex is a non-steroidal anti-inflammatory drug (NSAID). It is a specific type of NSAID known as a COX-2 inhibitor. NSAID medicines are used to treat pain and redness, swelling, and heat (inflammation) from medical conditions. Celebrex comes as a capsule to take by mouth. It is usually taken once or twice a day. Some common side effects of Celebrex include abdominal pain, diarrhea, nausea, upset stomach and cough.