A medical injection device is provided which includes a shield system and a syringe. The shield system includes a housing, a shield telescopically received in the housing and slidably coupled to the housing and a driver that pushes the syringe stopper to cause drug injection. The driver is equipped with sensing elements that automatically detect empty syringe. A spring resiliently urges the shield from a retracted position to an extended position shielding the needle. The syringe is coupled to the housing. The shield is positioned externally to the syringe and the driver. The shield includes flexible latches to keep its position relative to the housing during storage and use. The axial movement of the driver in respect to the syringe causes an automatic release of the spring by sensors when the syringe is empty, allowing the spring to move and lock the shield in the extended position after use.
