A frequently recounted episode in early modern medicine concerns the physician Helvetius's introduction of ipecacuanha to French medical practice after curing Louis XIV's son of dysentery using this medicinal drug. To this day, the Helvetius story remains riven with contradictions, obscurity, and confusion, even down to the nature of the drug involved. This article, challenging histories of “information” as homogeneous and neutral, explores how Helvetius's reputation as a physician and pharmaceutical entrepreneur was crafted through print and correspondence. Rather than seeking (...) to establish a definitive account of “what actually happened,” it addresses the ways in which different media shaped and mediated the politics of knowledge surrounding Helvetius and his drug. Considerations of intellectual and commercial property inflected medical knowledge in different ways, producing distinct strategies of publicity. While Helvetius capitalized on courtly connections to promote himself and his drug, rivals eyed the Republic of Letters as an alternate route for establishing natural knowledge-claims. Yet the arch-newsmonger of the Republic of Letters, Leibniz, elected to preserve the connection between Helvetius and ipecacuanha in print. I argue that Leibniz's actions stemmed from a view of the public domain that downplayed discovery and emphasized disclosure of medical secrets in the public interest. (shrink)