This article focuses on the hierarchical structure of users of a synthetic progestin, Homodeor and its effects on the construction of a pharmacovigilance plan by a French health agency, at a time when an institutional desire is being expressed to work more closely with all patient associations. This case study is mainly on a qualitative survey led by interviewing agents, health professionals and user representatives, which aimed to explore the relationships and representations developed around this issue. Despite the diversity of progestin use, a hierarchy between the different user groups was gradually established. The pharmacovigilance measures were designed for a specific group of patients, presented as the ideal users of the drug. The case of Homodeor makes it possible to highlight the dynamics of competition between groups of patients, and more broadly, the challenges of taking minority groups into account in health policies in the light of their development context.