A fluid applicator is fed by a fluid delivery arrangement containing an energy storage such as a pressure vessel. The gas pressure acts on a container that has been prefilled with the ejection fluid. The fluid to be ejected is thus subject to constant pressure. With a valve, the user can initiate the ejection of the desired amount of fluid with constant intensity. The check valve may also be a regulating valve which can be used by the user to vary the intensity of the effect. The user need only release the system, e.g., by puncturing the pressure vessel, to then be able to directly inject the fluid in a defined or metered manner via the probe, i.e., the fluid applicator. It is also possible to configure the entire injection device as a single-use system and to prefill the fluid applicator up to its fluid exit opening.