Seal for a prefilled medical jet injection device

A sealing membrane 20 on a nozzle 10 for a jet injection device is adapted to seal off the nozzle orifice 12 by having a sealing rim 22 surrounding the nozzle orifice 12, which ensures a distinct closure of the nozzle orifice 12 to protect the nozzle geometry against damage and dirt and to protect the drug 30 contained in the cartridge 10 against contamination. The sealing rim 22 can narrowly enclose the nozzle orifice 12, or in case an adhesive 14 is applied to the nozzle face to ensure skin retention during injection, the sealing rim 22 can run in the middle of the adhesive covered area or entirely outside the adhesive covered area to protect the adhesive as well. A third sealing member 23 can also be provided to give a third distinct closure assurance in case the primary and secondary sealing membrane 20 is damaged. The third sealing member 23 can be one or more plug(s) adapted to press fit inside the nozzle orifice.