A needle tip assembly for a pre-loaded syringe or a pen needle injection device. The needle tip assembly includes a body comprising a double-ended needle and being installable and removable from the pre-loaded syringe or pen needle injection device. A needle cap is configured to cover a skin puncturing end of the double-ended needle and is removable to exposed the skin puncturing end. An outer cover is structured and arranged to at least install the body onto the pre-loaded syringe or pen needle injection device and remove the body from the pre-loaded syringe or pen needle injection device after the outer cover is re-installed. The body is lockable to the outer cover upon one of re-installation of the outer cover and prior to the body being removed from the pre-loaded syringe or pen needle injection device.