A drug delivery device 100 comprising: a main exterior body 102; an interior body 104 axially moveable with respect to the main exterior body 102; a dual-chamber reservoir 108 arranged in the interior body 104 and axially moveable with respect to the interior body 104, the dual-chamber reservoir 108 comprising (i) a first chamber 114 holding a first medicament 116 and (ii) a second chamber 118 holding a second medicament 120; a needle 110 in fluid communication with the dual-chamber reservoir 108; and a plunger 112, wherein axial movement of the interior body 104 in a distal direction with respect to the main exterior body 102 activates the drug delivery device 100, and wherein, after activation of the drug delivery device 100, the plunger 112 is configured to (i) move the dual-chamber reservoir 108 a given distance in a proximal direction with respect to the interior body 104 so that a proximal end of the needle 110 extends out of the interior body 104 and (ii) after moving the dual-chamber reservoir 108 the given distance, move in the proximal direction with respect to the dual-chamber reservoir 108 so as to eject from the needle 110 the first medicament 116 followed by the second medicament 120; characterized in that the drug delivery device 100 comprises a first stopper 115 slidably arranged in the dual-chamber reservoir 108; and a second stopper 119 slidably arranged in the dual-chamber reservoir 108, wherein the first chamber 114 is between the first stopper 115 and a proximal end of the reservoir 108, and wherein the second chamber 118 is between the first stopper 115 and the second stopper 119; the drug delivery device 100 further comprises one of (a) a ruptureable membrane 160 separating the first chamber 114 from the second chamber 118; or (b) a conduit 204 disposed in the first chamber 114, wherein the conduit 204 is configured to establish fluid communication with the second chamber 118 during an injection process, wherein the conduit comprises at least one conduit needle configured to penetrate the first stopper and establish the fluid communication with the second chamber. a main exterior body 102; an interior body 104 axially moveable with respect to the main exterior body 102; a dual-chamber reservoir 108 arranged in the interior body 104 and axially moveable with respect to the interior body 104, the dual-chamber reservoir 108 comprising (i) a first chamber 114 holding a first medicament 116 and (ii) a second chamber 118 holding a second medicament 120; a needle 110 in fluid communication with the dual-chamber reservoir 108; and a plunger 112, wherein axial movement of the interior body 104 in a distal direction with respect to the main exterior body 102 activates the drug delivery device 100, and wherein, after activation of the drug delivery device 100, the plunger 112 is configured to (i) move the dual-chamber reservoir 108 a given distance in a proximal direction with respect to the interior body 104 so that a proximal end of the needle 110 extends out of the interior body 104 and (ii) after moving the dual-chamber reservoir 108 the given distance, move in the proximal direction with respect to the dual-chamber reservoir 108 so as to eject from the needle 110 the first medicament 116 followed by the second medicament 120; characterized in that the drug delivery device 100 comprises a first stopper 115 slidably arranged in the dual-chamber reservoir 108; and a second stopper 119 slidably arranged in the dual-chamber reservoir 108, wherein the first chamber 114 is between the first stopper 115 and a proximal end of the reservoir 108, and wherein the second chamber 118 is between the first stopper 115 and the second stopper 119; the drug delivery device 100 further comprises one of (a) a ruptureable membrane 160 separating the first chamber 114 from the second chamber 118; or (b) a conduit 204 disposed in the first chamber 114, wherein the conduit 204 is configured to establish fluid communication with the second chamber 118 during an injection process, wherein the conduit comprises at least one conduit needle configured to penetrate the first stopper and establish the fluid communication with the second chamber.