Disorders due to use of unknown or unspecified psychoactive substances

**Definition:** Disorders due to use of unknown or unspecified psychoactive substances are characterised by the pattern and consequences of psychoactive substance use when the specific substance is unknown or unspecified. These categories may be used in clinical situations in which it is clear that the disturbance is due to substance use but the specific class of substance is unknown. Once the relevant substance is identified, the disturbance should be recoded under the appropriate substance class.