An injection device including a barrel having a medicament reservoir therein capable of fluid communication with a needle assembly at a distal end thereof and sealed at a proximal end thereof with a stopper. The injection device further includes a plunger rod having a distal rod end which is couplable with said stopper, wherein, when the plunger rod is coupled to the stopper, forward axial movement of the plunger rod causes forward axial movement of the stopper coupled thereto into the medicament reservoir in order to expel medicament through the needle assembly. Further, the plunger rod can be decoupled from the stopper by applying a rearward axial force on the plunger rod, said rearward axial decoupling force being less than a rearward axial force required to move the stopper rearwardly with respect to the barrel.