An injection device comprising: a housing adapted to receive a syringe having a reservoir portion and a discharge nozzle, so that the syringe is movable between a retracted position in which the discharge nozzle is contained within the housing and an extended position in which the discharge nozzle extends from the housing through an exit aperture ; a drive that acts upon the syringe to advance it from its retracted position to its extended position and discharge its contents through the discharge nozzle; a removable cap adapted to be connected to the housing for closing the exit aperture ; and a syringe carrier for carrying the syringe as it is advanced, wherein the syringe carrier comprises a sheath for surrounding the reservoir portion of the syringe , wherein the sheath has a first internal diameter along its length, and an intermediate section with a second internal diameter which is smaller than the first internal diameter so that a first end of the sheath is adapted to support the syringe between the reservoir portion and the discharge nozzle and prevent forward movement of the syringe in the syringe carrier , and characterised in that the removable cap is adapted to restrict movement of the syringe carrier in a direction towards the exit aperture when the removable cap is connected to the housing , wherein the cap provides a first interface for restricting movement of the syringe carrier in a direction towards the exit aperture and the syringe carrier provides a second interface that engages the first interface when the removable cap is connected to the housing , wherein the first interface and second interface each comprise a planar surface. a housing adapted to receive a syringe having a reservoir portion and a discharge nozzle, so that the syringe is movable between a retracted position in which the discharge nozzle is contained within the housing and an extended position in which the discharge nozzle extends from the housing through an exit aperture ; a drive that acts upon the syringe to advance it from its retracted position to its extended position and discharge its contents through the discharge nozzle; a removable cap adapted to be connected to the housing for closing the exit aperture ; and a syringe carrier for carrying the syringe as it is advanced, wherein the syringe carrier comprises a sheath for surrounding the reservoir portion of the syringe , wherein the sheath has a first internal diameter along its length, and an intermediate section with a second internal diameter which is smaller than the first internal diameter so that a first end of the sheath is adapted to support the syringe between the reservoir portion and the discharge nozzle and prevent forward movement of the syringe in the syringe carrier , and characterised in that the removable cap is adapted to restrict movement of the syringe carrier in a direction towards the exit aperture when the removable cap is connected to the housing , wherein the cap provides a first interface for restricting movement of the syringe carrier in a direction towards the exit aperture and the syringe carrier provides a second interface that engages the first interface when the removable cap is connected to the housing , wherein the first interface and second interface each comprise a planar surface. <EOS>