A medical skin applicator apparatus (500, 600, 700, 800, 900), which comprises: an outer housing (534, 608) defining a longitudinal axis; a fluid housing (506, 610, 706, 802, 910) having a fluid chamber for storing a medical agent, the fluid housing having a penetrable wall (510, 804, 908) to permit access to the fluid chamber and release of the medical agent therefrom; an applicator head (504, 620) mounted to the outer housing in longitudinal fixed relation therewith, the applicator head including an applicator frame (548, 622, 822) and an applicator member (550, 614, 714, 856) mounted to the applicator frame, the applicator frame having an internal penetrating member (558, 820) dimensional to penetrate the penetrable wall of the fluid housing, thereby to permit the medical agent to be dispensed from the fluid chamber and applied to the patient with the applicator member; characterised by: the fluid housing being enclosed within the outer housing, and adapted for longitudinal movement relative to the applicator head and within the outer housing from a first, transit position to a second, actuated position to cause penetration of the penetrable wall with the penetrating member, the fluid housing being enclosed within the outer housing in both first and second positions; and a manually-engageable member (530, 606, 710) connected to the fluid housing and extending beyond the outer housing, the manually-engageable member being depressible to cause longitudinal movement of the fluid housing to the second, actuated position, the manually engageable member including means for releasably retaining the fluid housing (506, 610, 706, 802, 910) in the first, transit position. an outer housing (534, 608) defining a longitudinal axis; a fluid housing (506, 610, 706, 802, 910) having a fluid chamber for storing a medical agent, the fluid housing having a penetrable wall (510, 804, 908) to permit access to the fluid chamber and release of the medical agent therefrom; an applicator head (504, 620) mounted to the outer housing in longitudinal fixed relation therewith, the applicator head including an applicator frame (548, 622, 822) and an applicator member (550, 614, 714, 856) mounted to the applicator frame, the applicator frame having an internal penetrating member (558, 820) dimensional to penetrate the penetrable wall of the fluid housing, thereby to permit the medical agent to be dispensed from the fluid chamber and applied to the patient with the applicator member; characterised by: the fluid housing being enclosed within the outer housing, and adapted for longitudinal movement relative to the applicator head and within the outer housing from a first, transit position to a second, actuated position to cause penetration of the penetrable wall with the penetrating member, the fluid housing being enclosed within the outer housing in both first and second positions; and a manually-engageable member (530, 606, 710) connected to the fluid housing and extending beyond the outer housing, the manually-engageable member being depressible to cause longitudinal movement of the fluid housing to the second, actuated position, the manually engageable member including means for releasably retaining the fluid housing (506, 610, 706, 802, 910) in the first, transit position. the fluid housing being enclosed within the outer housing, and adapted for longitudinal movement relative to the applicator head and within the outer housing from a first, transit position to a second, actuated position to cause penetration of the penetrable wall with the penetrating member, the fluid housing being enclosed within the outer housing in both first and second positions; and a manually-engageable member (530, 606, 710) connected to the fluid housing and extending beyond the outer housing, the manually-engageable member being depressible to cause longitudinal movement of the fluid housing to the second, actuated position, the manually engageable member including means for releasably retaining the fluid housing (506, 610, 706, 802, 910) in the first, transit position.