The invention relates to an injection device for injecting a liquid drug. The injection device comprises a housing assembly supporting a non-removable cartridge having an interior chamber containing the liquid drug to be injected and a reusable needle cannula connected to the cartridge. A needle shield assembly provided with a cleaning chamber containing a volume of a cleaning agent for cleaning at least the distal tip of the needle cannula between subsequent injections is further provided. The needle shield assembly is axially movable in a proximal direction in relation to the housing assembly from a first position to a second position upon rotation of at least a part of the needle shield assembly, wherein the first position is a position in which the distal tip of the needle cannula is located inside the cleaning chamber thereby cleansing the distal tip of the needle cannula, and the second position is a position in which the distal tip of the needle cannula is located outside and distal to the cleaning chamber for equalizing the pressure in the cartridge.