Abstract
Illicit drug use remains a global concern, requiring effective detection methods to counter evolving concealment strategies. Natural drugs derived from plants typically retain distinct odorous volatile organic compounds (VOCs), while synthetic drugs emit noticeable scents due to additives or specific manufacturing processes. Indeed, trained sniffer dogs exhibit behavioral alerts, such as sitting near or scratching, when detecting substances such as marijuana, cocaine, heroin, and amphetamine. In this review, we focus on the intricate relationship between illicit drugs and their characteristic odors, highlighting VOC markers associated with both natural (cannabis and cocaine) and synthetic drugs (heroin, MDMA, fentanyl, and methamphetamine). Additionally, the detection of odors derived from illicit drugs is covered, from traditional methods involving sniffer dogs to emerging technologies such as electronic noses. Accordingly, this review offers insights into the odorous fingerprints of illicit drugs for continued research to refine innovative noncontact detection technologies for forensic and public health applications.