Jyseleca, known generically as filgotinib, is a medication primarily used in the treatment of moderate to severe rheumatoid arthritis (RA) in adults who have had an inadequate response or intolerance to one or more disease-modifying antirheumatic drugs (DMARDs). It belongs to a class of medications known as Janus kinase (JAK) inhibitors, which work by blocking the activity of one or more of the Janus kinase family of enzymes, thereby interfering with the JAK-STAT signaling pathway that plays a key role in the inflammatory process of rheumatoid arthritis. By doing so, Jyseleca helps reduce inflammation, pain, and joint damage associated with RA. It is administered orally and is available in tablet form. Like all medications, it can have side effects, and its use should be closely monitored by a healthcare professional.