Xeljanz (generic: tofacitinib) is a prescription medication used to treat rheumatoid arthritis in adult patients who have been treated with methotrexate without success. Rheumatoid arthritis is a disease of the immune system. Xeljanz belongs to a group of drugs called JAK inhibitors which work by suppressing the immune system against the damaging inflammation of rheumatoid arthritis.

This medication comes in tablet form and is taken once or twice daily, with or without food.

Common side effects of Xeljanz include runny or stuffy nose, headaches, and diarrhea.