On February 20, 1947, public-health officials in the United States concluded that several deaths were caused by a counterfeit or adulterated sulfanilamide preparation—an early sulfonamide antibiotic widely used in the 1930s and 1940s. Investigations at the time traced fatalities and serious poisonings to medicines that either lacked the stated active ingredient or contained harmful contaminants introduced during illicit production or diversion. These findings represented a formative moment in recognizing the lethal risk posed by counterfeit or adulterated pharmaceuticals and helped shape later regulatory and enforcement responses. Background Sulfanilamide and related sulfonamide drugs were among the first broadly effective antimicrobials available before penicillin became widely distributed. They were commonly used for infections and appeared in a range of proprietary and prescription products. The high demand for effective antimicrobials, combined with postwar shortages and uneven regulation, created conditions in which substandard, adulterated, or impersonating products could reach consumers. The 1947 confirmations The specific incidents in early 1947 involved clusters of severe poisoning and death temporally associated with use of sulfanilamide-containing preparations. Medical examiners and public-health laboratories analyzed specimens and implicated products that were either mislabeled or contaminated. Published contemporary reports and public-health bulletins described these conclusions and warned clinicians and the public. While reporting practices and terminology of the era sometimes used overlapping terms—"adulterated," "spurious," or "counterfeit"—the confirmed outcome in these cases was that commercially distributed medicines were directly responsible for fatalities. Impact on public health and regulation These events reinforced an emerging understanding that medicines sold on the market could be not only ineffective but actively dangerous. In the United States, the 1938 Federal Food, Drug, and Cosmetic Act had already expanded regulatory authority over drugs, requiring safety demonstrations for new products. However, enforcement resources and testing capabilities were limited, and illicit or counterfeit production sometimes evaded oversight. The 1947 confirmations contributed to sustained efforts by public-health authorities, professional groups, and law enforcement to improve surveillance, laboratory capacity, and prosecution of those producing or distributing harmful medicines. International and historical context Counterfeit and adulterated medicines are an older problem; adulteration of remedies dates back centuries. What makes the 1947 U.S. cases noteworthy in modern public-health history is the combination of laboratory confirmation tying specific products to deaths and the formal recognition by health authorities that commercially distributed medicines could be lethal when counterfeit or contaminated. Comparable problems occurred elsewhere and continued in subsequent decades, prompting international cooperation and later initiatives—such as improved quality control, pharmaceutical serialization, and global regulatory harmonization—to reduce the risk. Limitations and sources Contemporary terminology and record-keeping vary, and some historical sources use terms like "spurious" or "adulterated" where modern scholars would use "counterfeit." This summary reflects documented 1947 public-health conclusions in the United States tying specific sulfanilamide products to fatal outcomes; it does not claim exhaustive global primacy for that year. Primary sources include public-health bulletins, medical-journal reports, and contemporaneous regulatory communications. For detailed archival references, consult published 1940s public-health reports and historical analyses of pharmaceutical regulation. Legacy The 1947 confirmations underscored the need for vigilant regulation, laboratory surveillance, and public awareness about drug quality. They form part of a longer history that informed mid-20th-century strengthening of drug-safety systems and remain a reminder that medicine quality is essential to patient safety.