Naproxen is a nonsteroidal anti-inflammatory drug (NSAID) that is used to relieve pain, inflammation, and stiffness caused by various conditions. It works by reducing hormones that cause inflammation and pain in the body. Naproxen is available in both prescription and nonprescription forms. Prescription naproxen is used to relieve pain, tenderness, swelling, and stiffness caused by osteoarthritis, rheumatoid arthritis, juvenile arthritis, and ankylosing spondylitis. It is also used to relieve shoulder pain caused by bursitis, tendinitis, gouty arthritis, and pain from other causes, including menstrual pain. Nonprescription naproxen is used to reduce fever and to relieve mild pain from headaches, muscle aches, arthritis, menstrual periods, the common cold, toothaches, and backaches. Naproxen is also sometimes used to treat Pagets disease of bone and Bartter syndrome. However, it is important to note that naproxen can increase the risk of fatal heart attack or stroke, especially if used long term or taken at high doses, or if the patient has heart disease.