`titrebSubutex®, a drug, but what is a drug ? Outline of a semiotic anthropology of psychotropic substances`/titrebOpioid substitution treatments (OST) were implemented in France in the mid-1990s within a controversial context. Because of the health and political situation of the time, a pharmaceutical company found in an opportunity to obtain market approval for HDB. The paradigm for addictions care changed in France, and later assessments found the impact of this change to be globally positive. However, studies show that various forms of HDB misuse and its use as a “drug” have been reported. But then, what is a drug ? To define drugs as what a society considers as such does not allow us to answer this question, as long as the responsibility of placing the boundary between medications and drugs`np pagenum="053"/b falls on normative discourse. Yet, the challenge is to understand and explain why and how a medicinal product becomes a drug by the reconfiguration of its uses. HDB is a contemporary, exemplary case of this process of reconfiguration. But what is the origin of this process ?In the early 19th century, the English opium addict Thomas De Quincey gave evidence in his “confessions” of a practice that was spreading at the time. The book was a great success and its text is the canonical story of a myth that establishes a new and irreversible bond between Homo sapiens and psychotropic drugs. For the anthropologist, myths are narratives that, by fixing signs, establish forms to donate meaning. Semiotic anthropology studies how culture is considered as a way to donate meaning. Based on this epistemological programme, we will analyse the case of HDB in France from the perspective of De Quincey with opium. Returning to this originating source allows us to reconsider various current discourses on “drugs” and psychotropic substances. This article aims to clarify the foundational aspect of the literary gesture of the “English Opium-Eater”, and to examine what it becomes 200 years later with the introduction of HDB. One widespread idea is that drugs are a myth, a mere social construction, and that “they do not exist”. Yet, as a symbolic form it establishes conditions of possibility of psychotropic drugs use. This symbolic form will be shaped for its own sake, in a variety of forms, by countless language, technical, and social interaction practices.