The invention provides a injection device for administering an injectable product, including a base section adapted to receive a container from which a product dose is dispensed through a needle by displacement of a piston in the container, and a drive unit including a driven member, a drive element and a damping arrangement, the drive unit for applying a force to advance the piston in the container to dispense a dose, wherein the damping arrangement generally counteracts the drive force and counter forces. The invention also encompasses a needle safety sleeve and a blocking structure for use with injection devices.