Tofacitinib citrate is a Janus kinase (JAK) inhibitor used primarily in the treatment of autoimmune and inflammatory conditions, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS), and ulcerative colitis (UC). It works by selectively inhibiting JAK enzymes, which are involved in cytokine signaling pathways that drive immune responses and inflammation. This mechanism helps reduce joint pain, swelling, stiffness, and structural damage in RA and PsA patients, while managing intestinal inflammation, improving remission rates, and reducing flare-ups in UC and AS. It may also be used off-label or investigatively for other conditions like Crohn's disease where standard therapies fail. Administered orally, it provides convenience for long-term management. Use requires medical supervision due to potential serious side effects, including increased risk of infections, malignancies, and cardiovascular events.