The invention relates to a discharge tube which, according to the invention, contains a further radiation-emitting substance which has at least one emission line in a spectral region of low intensity of the spectrum which is predetermined by the remaining substances. The operation of lamps using the discharge tubes according to the invention can be controlled by detection of this emission line or these emission lines. In consequence, it is possible to ensure that only tested discharge tubes, according to the invention, whose life has not been exceeded are used, as a result of which damage to health during medical or cosmetic use, or defects in the case of technical production methods, resulting from irradiation from using unsuitable discharge tubes are prevented.