The invention relates to a UV-C sterilizing lamp for the treatment of a medium with UV-C radiation in order to kill the microorganisms contained therein by means of at least one UV-C emitter (2). The emitter has an elongated emitter foundation (3) and at least one electrical connection (4), and a base (5) holding the UV-C emitter (2). The at least the emitter foundation (3) of the UV-C emitter (2) is surrounded by a flexible protective cover (6), which is radiolucent to UV-C radiation.