Illicit drug


  • Scheduled drug

In DrugBank this status is given to drugs whereby their use has been prohibited due to either the stimulation or inhibition of the central nervous system or due to the production of hallucinogenic effects.1 Illicit drugs are often scheduled drugs, whereby they are approved but are limited in their distribution or have additional constraints on how they can be prescribed.

In the US, drugs are scheduled according to the following system:

  • Schedule I: no currently accepted medical use in the United States as well as a lack of accepted safety for use under medical supervision and a high potential for abuse.
  • Schedule II/IIN: high potential for abuse which may lead to severe psychological or physical dependence.
  • Schedule III/IIIN: less potential for abuse than substances in Schedules I or II. Abuse may lead to moderate or low physical dependence or high psychological dependence.
  • Schedule IV: lower potential for abuse compared to Schedule III drugs.
  • Schedule V: lower potential for abuse compared to Schedule IV drugs. These consist primarily of products which contain limited quantities of certain narcotics.

In Canada, drugs are scheduled according to the following system:

  • Prescription
  • Prescription Recommended
  • Schedule G (control drugs)
  • Schedule G (CDSA III)
  • Schedule G (CDSA IV)
  • Schedule C (for example, radiopharmaceutical drugs)
  • Schedule D (biological products)
  • Narcotic
  • Narcotic (CDSA I)
  • Narcotic (CDSA II)
  • Targeted (CDSA IV)
  • CDSA Recommended - Undergoing Regulatory Amendment to add this new substance to Controlled Drugs Substances Act
  • OTC - unscheduled over the counter drugs
  • Ethical: a drug that, in accordance with Federal Legislation, does not require a prescription, but that is generally prescribed by a medical practitioner. Examples include MRI contrast agents, hemodialysis solutions, and nitroglycerine.


  1. Uutela A. (2001). International encyclopedia of the social & behavioral sciences. Elsevier.