Rheumatoid arthritis is an autoimmune disorder that occurs when the immune system mistakenly attacks healthy tissue in the joints, causing inflammation and pain. Unlike osteoarthritis, which is caused by wear-and-tear damage, rheumatoid arthritis affects the lining of the joints, causing painful swelling that can eventually result in bone erosion and joint deformity. The exact cause of rheumatoid arthritis is unknown, but researchers believe that certain genes may make individuals more likely to develop the disease, and that environmental factors such as smoking, physical or emotional stress, or exposure to a virus or bacteria may trigger the immune system to attack the joints. Risk factors for rheumatoid arthritis include genetics, hormones, and environmental factors. Symptoms of rheumatoid arthritis may vary in severity and can include joint pain, swelling, stiffness, and loss of function, as well as fatigue, fever, and weight loss. The disease can also affect other parts of the body, such as the skin, eyes, lungs, heart, and blood vessels. While there is no cure for rheumatoid arthritis, treatment options include medication, physical therapy, and lifestyle changes to manage symptoms and prevent joint damage. It is important to see a doctor if you have persistent discomfort and swelling in your joints.