4) JAK inhibitor drugs
As mentioned before, the main pathology is genetic, and solving the genetic mutation remains the optimal method of the therapy. Two drugs have been approved as JAK inhibitors for the treatment of polycythemia which are ruxolitinib and fedratinib. They are, however, only used in case of contraindications to hydroxyurea or failure of treatment. The reason behind that is that there is an increased risk of side effects such as anemia and severe platelet deficiency experienced in as much as fifth of patients receiving those drugs.Their main advantage is that they achieve greater and long-lasting effects compared to other drugs including reduction in the size of the spleen. It is also reported that fedaratinib can relieve myelofibrosis resulting from polycythemia.