The purpose of this study was to explore how students interpret and negotiate menstruation in PE in online forums. We conducted a qualitative discourse analysis of 12 threads from 4 different German-language online forums, in which menstruation in PE is discussed by students. Our goal was to analyse which topics structure this online discourse and how menstruation in PE is constructed as a discourse phenomenon. The study found that participation in PE during menstruation and the use of hygiene products are the dominant topics, with swimming in PE gaining particular attention. The results further detail that students' online posts invoke specific causes, conditions, consequences, and strategies for dealing with menstruation in PE. The results indicate that students posting in online forums mainly interpret menstruation as an individual, shameful, restrictive, and unpleasant issue, stabilising norms of silence and concealment. Future research and pedagogical approaches must account for this.