A microneedle injection apparatus comprising: a housing having a base and a cavity that extends through the base to define an opening in the base, wherein the base of the housing is configured to be positioned toward a skin surface; a microneedle array holder configured to hold a microneedle array within the cavity of the housing, the microneedle array holder configured to be at least partially located in the cavity of the housing and movable with respect to the opening in the base of the housing between a retracted position in which the microneedle array is recessed within the housing such that the microneedle array does not contact the skin surface when the base of the housing is positioned on the skin surface and the microneedle array is coupled to the microneedle array holder, and an extended position in which at least a portion of the microneedle array is positioned to contact the skin surface via the opening when the base of the housing is positioned on the skin surface and the microneedle array is coupled to the microneedle array holder; and an actuator movable with respect to the housing and the microneedle array holder between a first position and a second position to cause the microneedle array holder to move from the retracted position to the extended position, wherein at least a portion of the actuator is located adjacent the base of the housing and is configured to be moved from the first position to the second position in response to the apparatus being pressed toward the skin surface, wherein when the actuator is in the first position, an outermost surface of the actuator extends beyond the base of the housing by a first distance, and when the actuator is in the second position, the outermost surface of the actuator does not extend beyond the base of the housing, or extends beyond the base of the housing by a second distance that is less than the first distance, and wherein the actuator is an inverted actuator located on a skin-facing surface of the apparatus. a housing having a base and a cavity that extends through the base to define an opening in the base, wherein the base of the housing is configured to be positioned toward a skin surface; a microneedle array holder configured to hold a microneedle array within the cavity of the housing, the microneedle array holder configured to be at least partially located in the cavity of the housing and movable with respect to the opening in the base of the housing between a retracted position in which the microneedle array is recessed within the housing such that the microneedle array does not contact the skin surface when the base of the housing is positioned on the skin surface and the microneedle array is coupled to the microneedle array holder, and an extended position in which at least a portion of the microneedle array is positioned to contact the skin surface via the opening when the base of the housing is positioned on the skin surface and the microneedle array is coupled to the microneedle array holder; and a retracted position in which the microneedle array is recessed within the housing such that the microneedle array does not contact the skin surface when the base of the housing is positioned on the skin surface and the microneedle array is coupled to the microneedle array holder, and an extended position in which at least a portion of the microneedle array is positioned to contact the skin surface via the opening when the base of the housing is positioned on the skin surface and the microneedle array is coupled to the microneedle array holder; and an actuator movable with respect to the housing and the microneedle array holder between a first position and a second position to cause the microneedle array holder to move from the retracted position to the extended position, wherein at least a portion of the actuator is located adjacent the base of the housing and is configured to be moved from the first position to the second position in response to the apparatus being pressed toward the skin surface, wherein when the actuator is in the first position, an outermost surface of the actuator extends beyond the base of the housing by a first distance, and when the actuator is in the second position, the outermost surface of the actuator does not extend beyond the base of the housing, or extends beyond the base of the housing by a second distance that is less than the first distance, and wherein the actuator is an inverted actuator located on a skin-facing surface of the apparatus.