An assembly for a drug delivery device (1) is described comprising a piston rod (12) adapted and arranged to be displaceable in a delivery direction for dispensing a dose of a drug (10) from the device (1), an energy storing member (16) which is adapted and arranged to store energy and to move the piston rod (12) in the delivery direction, and an interaction member (7) adapted and arranged to mechanically cooperate with the piston rod (12), wherein the interaction member (7) is displaceable between a first position and a second position with respect to the piston rod (12), wherein the interaction member (7) is configured to be moved from the first position towards the second position to increase a friction onto the piston rod (12) and, wherein the interaction member (7) is configured to be moved from the second position back into the first position to decrease the friction onto the piston rod (12). Furthermore, a drug delivery device (1) comprising the assembly is described.
