Very common side effects • bone, joint and muscle pain • elevations in blood levels of uric acid and certain enzymes • decreases in blood glucose • leukocytosis (an abnormally high number of white blood cells in the blood) • low level of blood platelets (which increases risk of bleeding or bruising) • low level of red blood cells (which can make the skin pale and cause weakness and breathlessness) • headache • nose bleed • enlarged spleen