ICD-11 Criteria for Disorders Due to Substance use or Addictive Behaviours (BlockL1‑6C4) Disorders due to substance use and addictive behaviours are mental and behavioural disorders that develop as a result of the use of predominantly psychoactive substances, including medications, or specific repetitive rewarding and reinforcing behaviours. Disorders due to substance use (BlockL2‑6C4) Disorders due to substance use include disorders that result from a single occasion or repeated use of substances that have psychoactive properties, including certain medications. Disorders related to fourteen classes or groups of psychoactive substances are included. Typically, initial use of these substances produces pleasant or appealing psychoactive effects that are rewarding and reinforcing with repeated use. With continued use, many of the included substances have the capacity to produce dependence. They also have the potential to cause numerous forms of harm, both to mental and physical heal