A prefilled injection device for injecting a pharmaceutical liquid drug containing a preservative, comprising: - a housing supporting a cartridge permanently embedded in the injection device and having an interior chamber containing the pharmaceutical preservative containing liquid drug to be injected, - a needle cannula permanently secured to the injection device and usable for multiple injections and having a front part with a tip and a back part, which back part is adapted to be in liquid communication with the interior chamber of the cartridge, and - a telescopic needle covering shield, which distally is provided with a reservoir confining a predetermined volume of a liquid for cleaning at least the tip of the needle cannula between subsequent injections, and which telescopic needle covering shield is urged distally into a first position by a first resilient member and moved proximally against the bias of the first resilient member into a second position during injection; - the first position being a position in which, the tip of the front part of the needle cannula is located inside the reservoir, and - the second position being a position in which, the tip of the front part of the needle cannula is located outside the reservoir and distally to the reservoir, and wherein, the predetermined volume of liquid confined in the reservoir of the telescopic needle covering shield is either phenol or metacresol or any combination thereof, being the same preservative as present in the pharmaceutical preservative containing liquid drug contained in the chamber of the cartridge. - a housing supporting a cartridge permanently embedded in the injection device and having an interior chamber containing the pharmaceutical preservative containing liquid drug to be injected, - a needle cannula permanently secured to the injection device and usable for multiple injections and having a front part with a tip and a back part, which back part is adapted to be in liquid communication with the interior chamber of the cartridge, and - a telescopic needle covering shield, which distally is provided with a reservoir confining a predetermined volume of a liquid for cleaning at least the tip of the needle cannula between subsequent injections, and which telescopic needle covering shield is urged distally into a first position by a first resilient member and moved proximally against the bias of the first resilient member into a second position during injection; - the first position being a position in which, the tip of the front part of the needle cannula is located inside the reservoir, and - the second position being a position in which, the tip of the front part of the needle cannula is located outside the reservoir and distally to the reservoir, - a telescopic needle covering shield, which distally is provided with a reservoir confining a predetermined volume of a liquid for cleaning at least the tip of the needle cannula between subsequent injections, and which telescopic needle covering shield is urged distally into a first position by a first resilient member and moved proximally against the bias of the first resilient member into a second position during injection; - the first position being a position in which, the tip of the front part of the needle cannula is located inside the reservoir, and - the second position being a position in which, the tip of the front part of the needle cannula is located outside the reservoir and distally to the reservoir,