Osteoarthritis (OA) is a disease of the bone joints that can cause severe pain and swelling. The cartilage around the ends of your bone joints wears away over years of use and leaves the bones rubbing against each other. This can make them inflamed and painful.Your doctor may ask you to make lifestyle changes like exercise, losing weight, and changing your eating habits. In addition to those options, there are several medications that may help you. Some are available over the counter while others need a prescription. They can be pills, creams, lotions, or injections.