Peficitinib is primarily used in the treatment of autoimmune conditions, particularly rheumatoid arthritis. It works by inhibiting Janus kinases (JAK), which are enzymes involved in the inflammatory process. By blocking these enzymes, peficitinib helps reduce inflammation and alleviate symptoms such as joint pain, swelling, and stiffness. It is often prescribed for patients who have not responded adequately to other disease-modifying antirheumatic drugs (DMARDs). Additionally, peficitinib is being studied for its potential use in other inflammatory and immune-related disorders, offering hope for expanded therapeutic applications in the future.