A pre-filled disposable injection device having a needle cannula mounted thereon, comprising: - A housing containing a non-exchangeable cartridge for storing a liquid drug sufficient for a number of injections, and which cartridge is permanently embedded in the injection device, - a settable dose setting mechanism having a dose setting button whereby a user can set a size of a dose to be injected, - the needle cannula, which is maintained attached to the injection device between injections, comprises a front part having a tip for penetrating the skin of the user, a back part for penetrating into the cartridge, and a lumen usable for the passage of the liquid drug in the non-exchangeable cartridge through an initial injection followed by a successive number of injections, - a telescopic needle covering shield which can operate between a first position and a second position; - The first position being a position in which the telescopic shield is in an extended position covering the tip of the front part of the needle cannula, - The second position being a position in which the shield is retracted such that at least the tip of the front part of the needle cannula is exposed to perform an injection, and wherein resilient means are provided for automatically returning the shield to its first position following both the initial injection and any of the successive injections, whereby the injection device is characterized in that the shield is distally carrying a cleaner, wherein at least the lumen of the needle cannula is preserved in a sterile condition prior to the initial injection, and in which first position at least the tip of the front part of the needle cannula is contained within the cleaner to thereby prevent clogging of the lumen of the needle cannula. - A housing containing a non-exchangeable cartridge for storing a liquid drug sufficient for a number of injections, and which cartridge is permanently embedded in the injection device, - a settable dose setting mechanism having a dose setting button whereby a user can set a size of a dose to be injected, - the needle cannula, which is maintained attached to the injection device between injections, comprises a front part having a tip for penetrating the skin of the user, a back part for penetrating into the cartridge, and a lumen usable for the passage of the liquid drug in the non-exchangeable cartridge through an initial injection followed by a successive number of injections, - a telescopic needle covering shield which can operate between a first position and a second position; - The first position being a position in which the telescopic shield is in an extended position covering the tip of the front part of the needle cannula, - The second position being a position in which the shield is retracted such that at least the tip of the front part of the needle cannula is exposed to perform an injection, and - The first position being a position in which the telescopic shield is in an extended position covering the tip of the front part of the needle cannula, - The second position being a position in which the shield is retracted such that at least the tip of the front part of the needle cannula is exposed to perform an injection, and