A revelatory account of the “wonder drug” theriac, which became a powerful tool in the hands of medical and political authorities at the height of the Italian Renaissance. From the 1490s, one of the most influential remedies to circulate in Europe was the “wonder drug” theriac. Although it had been in use for centuries, theriac gained special importance in the Renaissance, when Italy became a major hub of its production and export. A quintessential example of Galenic pharmacy, theriac was used to treat everything from venomous bites and poisons to headaches, sore throats, fevers, palsy, and heart problems. Examining this pivotal period in the history of medicine, Barbara Di Gennaro Splendore shows how a panacea became a vehicle for political power as well as intellectual and commercial competition. So essential was theriac to good health that regimes in Bologna and Venice could secure popular support by asserting regulatory control over this “state drug.” Likewise, medical authorities relied on theriac to solidify their own legitimacy, through public ceremonies replete with music and choreography. Apothecaries and physicians engaged in spirited rivalry over branding and control of production, as well as disputes over optimal recipes, which included opium and viper flesh as well as dozens of other ingredients. Yet as Galenic science came into question in the late seventeenth century, the alliance between politics and pharmacy weakened. Physicians, in particular, grew hesitant over whether to continue promoting theriac at all. While the drug remained beloved, especially among the poor, its political power was significantly diminished by the nineteenth century. Offering a vivid window into the political history of medicine, The State Drug sheds new light on the fraught, age-old intersection of power and pharmacy.