(3S,4R)-Tofacitinib is primarily used in the treatment of autoimmune conditions, particularly rheumatoid arthritis. It works by inhibiting the Janus kinase (JAK) enzymes, which play a crucial role in the immune response. This inhibition helps reduce inflammation and slow the progression of joint damage in patients with rheumatoid arthritis. Additionally, it is effective in managing psoriatic arthritis, a condition that causes joint pain and swelling in people with psoriasis. Tofacitinib is also approved for the treatment of ulcerative colitis, where it helps to control symptoms and induce remission by modulating the immune system. In some cases, it is used off-label for other autoimmune disorders, providing relief where traditional therapies have failed. Its oral administration offers a convenient alternative to injectable biologics, improving patient compliance and quality of life.