Right shoulder pain and arm swelling may be sprain, but also may be frozen shoulder, rheumatoid arthritis and deep vein thrombosis and other diseases. 1. Sprain: If the right shoulder has been violently impacted, excessively pulled, or strenuous exercise, sprain is easy to occur, and then the symptoms of right shoulder pain and arm swelling will appear, accompanied by activity limitation. 2. Frozen shoulder: Frozen shoulder may be related to shoulder soft tissue degeneration, chronic injury, acute contusion, etc. It can be induced by long-term lack of activities, weather changes and cold, resulting in adhesion and dehydration of tendons and soft tissues around the shoulder joint, symptoms of pain and arm swelling, and joint stiffness and impaired movement. 3. Rheumatoid arthritis: this disease is considered to be related to genetic, autoimmune and other reasons, common triggering factors are smoking, pathogenic microbial infections. Typical symptoms are stiffness, swelling and pain in the joints. Commonly affected parts are shoulder and wrist, so some patients will have pain and swelling in the right shoulder. 4. Deep vein thrombosis: it may be due to thrombosis in the deep veins of the arm position, once the thrombosis is formed, it will lead to serious obstacles to venous return, and a large amount of venous blood will accumulate in the distal end leading to right shoulder pain and arm swelling. There are many reasons for right shoulder pain and arm swelling, patients need to go to the hospital in time to clarify the cause.