An Essay on the Effects of Opium, Considered as a Poison is a seminal medical treatise first published in 1786 by George Young, a Scottish physician. This comprehensive work delves into the physiological and pathological consequences of opium use, examining its role as both a medicinal agent and a dangerous poison. Drawing on clinical observations, case studies, and contemporary medical literature, Young meticulously analyzes the symptoms, progression, and outcomes of opium poisoning, offering detailed descriptions of its effects on the human body and mind. The essay begins with an exploration of opium’s historical use in medicine, highlighting its popularity as a painkiller and sedative. Young then shifts focus to the darker side of opium, documenting the various ways in which it can cause harm, from acute overdoses to chronic addiction. He discusses the signs of opium poisoning, such as stupor, respiratory depression, and eventual death, and provides guidance on distinguishing opium toxicity from other medical conditions. Throughout the book, Young emphasizes the importance of careful dosing and the dangers of indiscriminate use, warning both physicians and the public about the risks associated with this potent drug. He also addresses the challenges of treating opium poisoning, reviewing available antidotes and therapeutic interventions of his time. An Essay on the Effects of Opium, Considered as a Poison stands as an early and influential contribution to toxicology and pharmacology. It reflects the medical knowledge and concerns of the late 18th century, offering valuable insights into the historical context of opium use and abuse. The book remains a significant resource for historians of medicine, pharmacologists, and anyone interested in the complex legacy of opium in Western medical practice.