Rinvoq (upadacitinib) is a Janus kinase (JAK) inhibitor. It's used to treat certain inflammatory conditions, such as rheumatoid arthritis (RA), ulcerative colitis (UC), and eczema (atopic dermatitis). But it's not a first-choice option and typically only prescribed when other treatments haven't worked well. Rinvoq (upadacitinib) is taken by mouth, usually once daily. It's available as an extended-release tablet (Rinvoq) and an oral solution (Rinvoq LQ), but the two formulations aren't interchangeable. Side effects include a higher risk of infections, acne, and nausea.