What is back pain? Back pain is one of the most common medical problems in the United States. It might feel like a dull, constant ache or a sudden, sharp pain. Back pain can result from: An accident. A fall. Lifting something heavy. Changes that happen in the spine as you age. A disorder or medical condition. Treatment depends on the cause and symptoms of your pain. You can do things to improve your health and lower your chance of developing chronic (long-lasting) back pain.

What is reactive arthritis? Reactive arthritis happens when an infection causes joint pain and swelling. A bacterial infection in the digestive or urinary tract or the genitals usually triggers the condition, but arthritis symptoms typically do not start until a few weeks after you have recovered from the infection. The most common features of reactive arthritis are inflammation of the joints (especially the knees and ankles), eyes, and urinary tract, but not everyone gets all three, or they might not happen at the same time.

What is rheumatoid arthritis? Rheumatoid arthritis (RA) is a chronic (long-lasting) disease that mostly affects joints, such as the wrist, hands, feet, spine, knees, and jaw. In joints, RA causes inflammation that leads to: Pain. Swelling Stiffness. Loss of function. Rheumatoid arthritis is an autoimmune disorder because the immune system attacks the healthy joint tissues. Normally, the immune system helps protect the body from infection and disease. RA may cause you to feel unusually tired, to have occasional fevers, and to have a loss of appetite. It also may cause other medical problems in the heart, lungs, blood, nerves, eyes