S-Ruxolitinib is primarily used in the treatment of myeloproliferative disorders, such as polycythemia vera and myelofibrosis. It works by inhibiting the JAK1 and JAK2 enzymes, which are involved in the signaling pathways that promote the growth and survival of abnormal blood cells. This helps reduce symptoms like enlarged spleen, night sweats, and itching. Additionally, it is being explored for its potential in treating other conditions like graft-versus-host disease and certain autoimmune disorders due to its immunomodulatory effects. The compound's ability to target specific pathways makes it a valuable therapeutic option in managing these complex diseases.