‘I call on the god to grant us that most effective pharmakon, the best of all medicines: knowledge’. Thus writes Plato in Critias, the uncomplete work of the Greek philosopher where he discusses the Athenians’ resistance against Atlantis, a parable of the victory of the ‘good city’ versus the ‘decadent city’, of good knowledge versus falsehood. Pharmakon stands out in Plato’s argument as the paradigm capturing the drug/medicine, good/evil dichotomy, an ambiguity that triggered Jacques Derrida’s essay named Plato’s Pharmacy. In its linguistic journey from ancient Greek, pharmakon has acquired the meaning of ‘remedy’, ‘poison’ and ‘scapegoat’ at the same time. But does this ambiguity, which is semantic as much as it is semiotic, translate in contexts beyond the Western world, beyond the legacy of Greek civilisation? In modern Iran, there is a word/substance that captures pharmakon’s coexistence of otherwise incongruous meanings. That word/substance is opium, taryak: a drug-poison, a drug-medicine, and a scapegoat. This paper is a historical anthropology of the lifeworld of opium from the late 19th century Iran, when taryak/opium embodied different, contradictory beings at the same time: 1) It was the hakim’s (traditional physician) first line of intervention in response to the most diverse of his patient’s ailments, but also the cause of health conditions vaguely identified later as ‘addiction’; 2) it was the primary antidote to the snake’s venom, but also one of the most used means to poison an enemy or to commit suicide; 3) it was the self-remedy to physical distress and psychosomatic malaise, but also the increasing source of public concern, a scapegoat for the nation’s political and cultural shortcomings, an impediment to becoming a modern civilisation. The question of taryak/opium is an epitome of ontological politics concerning what is good and what is evil, what is life and life-inducing, from what is mortal, what is a panacea of all problems from what is a scapegoat for policy/polity failures. By discussing opium as the pharmakon in Iran’s public life and its troubled movement towards the foundation of the modern nation-state in 1925, the paper argues that the questions around the nature of what is pharmakon shows the intimate historical nexus between knowledge production about health and forms of political life. The paper is based on extensive archival documentation from 1880s to the late 1940s, including memoires, diaries, laws, medical reports and petitions on the question of opium and/or by people using opium.