The EU Biocidal Products Regulation (BPR) regulates the placing on the market and use of biocidal products. Biocidal products require an authorisation before they can be placed on the market. The active substances contained in the biocidal product must be approved beforehand. Questions repeatedly arise about the distinction between biocides and cleaning agents/detergents and about certain labelling obligations. In particular the question of how products are claimed and marketed, and which factors may lead to a cleaning product having to be authorised as a biocide under the BPR. Due to a lack of clarity in the regulations and the non-availability of guidelines, especially in borderline areas, this article attempts to differentiate between cleaning agents and a biocide application with a concrete example from the pulp and paper industry and to illustrate which circumstances are relevant.