Jakavi 20mg tablet contains the active constituent ruxolitinib. It is an anticancer agent that belongs to the class of kinase inhibitors. It is used to treat myelofibrosis (a rare type of bone marrow cancer that causes decreased blood cell production). It is also used to treat polycythemia vera (a type of blood cancer where the body produces too many red blood cells) in people who are resistant or cannot be treated successful hydroxyurea. The medicine is also indicated to treat acute graft versus host disease (a complication of transplant procedure that replaced diseased bone marrow with healthy bone marrow) previously treated unsuccessfully with steroid medications in adults and children 12 years of age. It is also used for treating chronic graft versus host disease in adults and children 12 years of age and older who were treated unsuccessfully with 1 or 2 other systemic treatments.