A controlled substance is generally a drug or chemical whose manufacture, possession and use is regulated by a government, such as illicitly used drugs or prescription medications that are designated by law. Some treaties, notably the Single Convention on Narcotic Drugs, the Convention on Psychotropic Substances, and the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, provide internationally agreed-upon "schedules" of controlled substances, which have been incorporated into national laws; however, national laws usually significantly expand on these international conventions.
The examples and perspective in this article or section might have an extensive bias or disproportional coverage towards one or more specific regions. (July 2017)
Some precursor chemicals used for the production of illegal drugs are also controlled substances in many countries, even though they may lack the pharmacological effects of the drugs themselves. Substances are classified according to schedules and consist primarily of potentially psychoactive substances and anabolic steroids. The controlled substances do not include many prescription items such as antibiotics.