Diclofenac is a nonsteroidalanti-inflammatory drug (NSAID) used to treat mild-to-moderate pain, and helpsto relieve symptoms of arthritis (eg, osteoarthritis or rheumatoid arthritis),such as inflammation, swelling, stiffness, and joint pain. This medicine doesnot cure arthritis and will only help you as long as you continue to take it. Thismedicine is also used to treat ankylosing spondylitis, which is a type ofarthritis that affects the joints in the spine, and other painful conditionssuch as menstrual cramps. Diclofenac is also used to treat acute migraineattacks, with or without aura, in adults. It will not prevent or lessen thenumber of migraine attacks.