Naproxen is used to relieve pain and swelling (inflammation) from various conditions. It is used to treat headaches, muscle aches, backaches, tendonitis, dental pain, and menstrual cramps. It also reduces pain, swelling, and joint stiffness caused by arthritis, bursitis, and gout attacks. Reducing these symptoms helps you do more of your normal daily activities. This medication is known as a nonsteroidal anti-inflammatory drug (NSAID).