A switchable rocker arm to control the lift of a valve bridge or of a single valve of a valve train group of an internal combustion engine; the switchable rocker arm being able to rotate around a first axis and comprising: a cam body, which is configured to be rotated by a cam; a valve body, which is configured to act upon the valve bridge or the single valve; wherein the switchable rocker arm can selectively be switched between a first configuration, in which the rotation of the cam body around the axis generates a movement of the valve body, and a second configuration, in which the rotation of the cam body around the axis does not generate any movement of the valve body.