in popular usage, illegal synthetic, laboratory-made chemicals. Although the term is not precisely defined, it is understood to refer to commonly abused drugs such as fentanyl, ketamine, LSD, PCP, quaaludes, methcathinone, and GHB (gammahydroxy butyrate), as well as to amphetamine derivatives such as Ecstasy (3,4, Methylenedioxymethamphetamine; MDMA) and methamphetamine. Designer drugs constitute a substantial proportion of the illegal drug market.

Designer drugs usually are synthesized for the first time in an attempt to create an analogue of some better-known chemical. Analogues of certain legal drugs have been produced by pharmaceutical companies in order to make the drugs safer, more effective, or more readily available to a mass public, and indeed the term designer drug originally referred to legal pharmaceuticals. It began to be applied to illegal substances in the 1980s, when authorities in the United States became concerned about the use of synthetic heroins (heroin) such as fentanyl. In either usage, the term echoed advertisements for designer jeans and carried connotations of the faddishness and the elite cachet of expensive consumer goods.

Illegal designer drugs aroused alarm because their production in clandestine laboratories thwarted efforts to control them by more usual means, such as import restrictions, and because they were thought to pose grave physical and psychological dangers to users. Some designer drugs were far stronger than the drugs for which they served as popular substitutes, which thus increased the likelihood of overdose. Also, minor errors in the synthetic process could result in substances very different from—and far more deadly than—the desired product.

The possibility of creating different designer versions of the same drug sometimes made regulation of designer drugs difficult. Legislators would sometimes pass laws prohibiting a substance used in a designer drug only to see a marginally different version appear, using substances not covered in the original law. In the United States this problem was addressed in the Anti-Drug Abuse Act of 1986, which contained a Controlled Substance Analogue Enforcement Act (commonly called the Designer Drug Act), which prohibited the manufacture of “substantially similar” analogues of banned chemicals.

In the United States, concern about designer drugs subsided in the mid-1980s, when crack cocaine was perceived to be a major problem. In the 1990s there were renewed fears regarding various synthetic drugs, especially Ecstasy and methamphetamine. Ecstasy, which was consumed by young people at dances known as “raves,” became a major component of youth subcultures. In the late 1990s, a new wave of concern focused on the so-called “date-rape drugs,” synthetic chemicals such as GHB (gamma hydroxybutyrate) and Rohypnol, which were used to render potential victims unconscious.