The nozzle has a nozzle cylinder (1) in which a piston rod (5) is movable with a piston (4), and a safety cylinder (2) surrounding the cylinder (1). A spring (3) is provided between the cylinders, and a retaining flange (12) is provided between the cylinders proximal end regions. The flange connects both the cylinders, and a releasing flange (51) detaches the connection between the cylinders. A release movement of the rod is enabled in a distal direction relative to the cylinder (1) during attachment of the piston to a distal front wall of the rod, in order to release the retaining flange.