Brand name; Orencia. Generic name; Abatacept. Classified as an immunosuppressant. It reduces symptoms of moderate to severe rheumatoid arthritis, used in the treatment of Rheumatoid arthritis. It works by weakening your immune system and decreasing inflammation. Clients who take Orencia may experience dizziness, headache, or mild pain at injection site. It is best to use caution around injection site.