A medication injector for dispensing liquid medications to people includes a container which is filled with the liquid and which has an opening at one end for dispensing the liquid and at least one pair of capacitive measuring electrodes disposed opposite each other in the outer region of the container, in particular on the wall, for determining the permittivity of the respective medium in the intermediate region between the measuring electrodes. The measuring electrodes are used by the injector to determine the fill level of the container. A shielding surrounds the measuring electrodes in the manner of a sheath, is disposed around the container, and reduces possible external interfering influences on the capacitive measurement, such as those resulting from contact, for example. Additionally, a contact sensor is provided which can indicate the measurement as invalid.