Dose setting mechanism for a drug delivery device, the mechanism comprising: a housing comprising a proximal and a distal end; a dose dial sleeve positioned at least partly within the housing and rotatable during dose setting and dose dispensing; a driver directly or indirectly connected to the dose dial sleeve and preferably threadedly engaged to a piston rod, and a lock-out component attached or otherwise fixed to the driver thereby following the axial movement of the driver, wherein the driver moves in a proximal axial direction relative to the housing during dose setting and in a distal axial direction relative to the housing during dose dispensing, characterized in that the lock-out component is a flexible disc element, wherein the extremities of the flexible disc element are deformed distally during dose setting and proximally during dose dispensing; in that a reduced diameter section at the housing forcing the flexible disc element to change from a second proximally biased concave condition into a first convex condition by elastically flipping its orientation, when the flexible disc element moves into the reduced diameter section during dose setting; and in that the flexible disc element is adapted to transform back to its second proximally biased concave condition after the flexible disc element moves out of the reduced diamenter section during dose setting corresponding to exceeding a predetermined minimum dose value, wherein the user is prevented from delivering a set dose by the flexible disc element if the flexible disc element is in the first convex condition, whereas, if the flexible disc element is in the free second proximally biased concave condition, the delivery of the set dose is allowed, wherein the length and position of the reduced diameter section at the housing controls the minimum dose value that must be set before it is allowed to deliver the set dose. a housing comprising a proximal and a distal end; a dose dial sleeve positioned at least partly within the housing and rotatable during dose setting and dose dispensing; a driver directly or indirectly connected to the dose dial sleeve and preferably threadedly engaged to a piston rod, and a lock-out component attached or otherwise fixed to the driver thereby following the axial movement of the driver, wherein the driver moves in a proximal axial direction relative to the housing during dose setting and in a distal axial direction relative to the housing during dose dispensing, characterized in that the lock-out component is a flexible disc element, wherein the extremities of the flexible disc element are deformed distally during dose setting and proximally during dose dispensing; in that a reduced diameter section at the housing forcing the flexible disc element to change from a second proximally biased concave condition into a first convex condition by elastically flipping its orientation, when the flexible disc element moves into the reduced diameter section during dose setting; and in that the flexible disc element is adapted to transform back to its second proximally biased concave condition after the flexible disc element moves out of the reduced diamenter section during dose setting corresponding to exceeding a predetermined minimum dose value, wherein the user is prevented from delivering a set dose by the flexible disc element if the flexible disc element is in the first convex condition, whereas, if the flexible disc element is in the free second proximally biased concave condition, the delivery of the set dose is allowed, wherein the length and position of the reduced diameter section at the housing controls the minimum dose value that must be set before it is allowed to deliver the set dose.