The present invention relates to a pen injecting device for delivering a liquid medicament comprising a pen body, a needle received in a first end of the pen body, an inner needle shield removeably located over the needle to enclose the needle, an outer needle shield removeably located over the inner needle shield to enclose the inner needle shield and a pen cap removeably attached to the first end of the pen body so as to enclose the outer needle shield. The pen cap comprises an arm depending from an inside surface of the cap and extending away from the first end of the pen body toward the inner and outer needle shields, the arm having a sharp end so that, as the cap is removed from the body, the sharp end of the arm grips the inner or outer needle shield to retain it in the cap and expose the needle.