Disorders due to use of unknown or unspecified psychoactive substances

Description

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. [1]

Diagnostic requirements

WHO clinical descriptions and diagnostic requirements [1,2].

Subcategories

• 6C4G.0 Episode of harmful use of unknown or unspecified psychoactive substances

  An episode of use of an unknown or unspecified psychoactive substance that has caused damage to a person’s physical or mental health or has resulted in behaviour leading to harm to the health of others. Harm to health of the individual occurs due to one or more of the following: (1) behaviour related to intoxication or withdrawal; (2) direct or secondary toxic effects on body organs and systems; or (3) a harmful route of administration. Harm to health of others includes any form of physical harm, including trauma, or mental disorder that is directly attributable to behaviour due to substance intoxication or withdrawal on the part of the person to whom the diagnosis of single episode of harmful use applies. This diagnosis should not be made if the harm is attributed to a known pattern of use of the unknown or unspecified psychoactive substance. [1]

  Essential (Required) Features:

  • An episode of use of unknown or unspecified psychoactive substances that has caused clinically significant damage to a person’s physical health (e.g., blood-borne infection from intravenous self-administration) or mental health, or has resulted in behaviour leading to harm to the health of others.
  • Harm to health of the individual occurs due to one or more of the following: (1) behaviour related to intoxication; (2) direct or secondary toxic effects on body organs and systems; or (3) a harmful route of administration.
  • Harm to health of others includes any form of physical harm, including trauma, or mental disorder that is directly attributable to behaviour due to Intoxication Due to Unknown or Unspecified Psychoactive Substances on the part of the person to whom the diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances applies.
  • Harm to health is not better accounted for by another medical condition or another mental disorder, including another Disorder Due to Substance Use (e.g., Substance Withdrawal).

  Note: Harm to the health of the person to whom the diagnosis applies includes injuries caused by behaviour related to intoxication (e.g., impulsive aggressive behaviour, psychomotor impairment leading to injury), acute health problems resulting from substance use (e.g., overdose, acute gastritis, the effects of hypoxia or prolonged hyperactivity or inactivity), and exacerbation or decompensation of pre-existing chronic health problems (e.g., hypertension, liver disease, or peptic ulceration). Harm may also result from a harmful route of administration (e.g., injecting drug use causing blood-borne virus infections, cocaine use causing a perforated nasal septum). The relevant diagnostic codes from other chapters of the ICD-11, including the chapter on Injury, Poisoning or Certain Other Consequences of External Causes, should be used to describe the specific health consequences of the harmful substance use.

  Harm to the health of others includes any form of physical harm, including trauma (e.g., impaired driving causing a motor vehicle accident, assaultive behaviour leading to bodily harm to another person) or mental disorder (e.g., Post-Traumatic Stress Disorder arising from an assault by the intoxicated individual) that is directly attributable to behaviour due to substance intoxication on the part of the person to whom the diagnosis of Episode of Harmful Psychoactive Substance Use applies.

  Additional Clinical Features:

  • There must be explicit evidence of harm to the individual’s physical or mental health, or of substance-related behaviour due to intoxication that has led to harm to the physical or mental health of others. There must also be a clear causal relationship between the harm to health and the episode of unknown or unspecified psychoactive substance use in question.
  • The likelihood of harm to self or others due behaviour related to intoxication varies substantially by substance. For example, such behaviour is unlikely to arise from caffeine or nicotine intoxication.
  • Unknown or Unspecified Psychoactive Substances use commonly occurs in the context of other mental disorders. An additional diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances can be made if the index episode of cannabis use has resulted in clinically significant harm to the individual’s physical health or has exacerbated or triggered an episode of a pre-existing mental disorder (e.g., a Manic or Depressive Episode or a psychotic episode).
  • A diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances often signals an opportunity for intervention, typically a low intensity intervention that can be implemented in a wide range of settings that is specifically aimed at reducing the likelihood of additional harmful episodes or of progression to Harmful Pattern of Use or Unknown or Unspecified Psychoactive Substance Dependence.
  • As more information becomes available indicating that the episode is part of a continuous or recurrent pattern of unknown or unspecified psychoactive substances use, or if additional harmful episodes occur, a diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances should be changed to Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances or Unknown or Unspecified Psychoactive Substance Dependence, as appropriate.

  Boundary with Normality (Threshold):

  • The diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances requires clinically significant harm to the individual’s physical or mental health or that of others. Examples of impact on physical or mental health that would not be considered clinically significant include mild hangover, brief episodes of vomiting, or transient depressed mood.
  • A range of social problems may be associated with an episode of substance use that are not sufficiently severe to constitute clinically significant harm to physical or mental health (e.g., missed appointments, arguments with loved ones). Such problems are not a sufficient basis for a diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances.

  Boundaries with Other Disorders and Conditions (Differential Diagnosis):

  • Boundary with Hazardous Use of Unknown or Unspecified Psychoactive Substances: Hazardous Use of Unknown or Unspecified Psychoactive Substances is classified in the chapter on ‘Factors Influencing Health Status or Contact with Health Services’ in the ICD-11 and not in the chapter on Mental, Behavioural, and Neurodevelopmental Disorders. Hazardous Use of Unknown or Unspecified Psychoactive Substances appreciably increases the risk of harmful physical or mental health consequences to the user or to others to an extent that warrants attention and advice from health professionals, but has not resulted in specific identifiable harm and therefore does not meet the diagnostic requirements for Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances.
  • Boundary with Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances: If the harm to health is a result of a known episodic or continuous pattern of substance use and all other diagnostic requirements are met, a diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances should be assigned. Substance use is generally considered to be following a pattern if there has been at least episodic or intermittent use over a period of at least 12 months. If harm is caused by use of unknown or unspecified psychoactive substances but no information is available about the pattern or history of substance use, a diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances may be assigned until such time as evidence for a pattern of use is ascertained.
  • Boundary with Unknown or Unspecified Psychoactive Substance Dependence: In Unknown or Unspecified Psychoactive Substance Dependence, individuals use unknown or unspecified psychoactive substances persistently despite harm and adverse consequences. Harm caused by such use may be similar to that observed in Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances. However, Unknown or Unspecified Psychoactive Substance Dependence also includes additional features of impaired ability to control use and increasing priority given to the substance use over other activities. Physiological features (e.g., tolerance) may also be present. If all diagnostic requirements for Unknown or Unspecified Psychoactive Substance Dependence are met, Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances should not be assigned.
  • Boundary with Intoxication Due to Unknown or Unspecified Psychoactive Substances: Intoxication Due to Unknown or Unspecified Psychoactive Substances is defined by unknown or unspecified psychoactive substances use that results in clinically significant transient unknown or unspecified psychoactive substances-specific symptoms. Recovery from Intoxication Due to Unknown or Unspecified Psychoactive Substances is generally complete and without physical or mental sequelae. If there is continuing damage or harm (e.g., the effects of hypoxia, the effects of prolonged hyperactivity or inactivity, tissue damage) due to an episode of Intoxication Due to Unknown or Unspecified Psychoactive Substances, a diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances may be assigned. If relevant at the time of the clinical encounter (e.g., in emergency settings), Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances may be diagnosed with an associated diagnosis of Intoxication Due to Unknown or Unspecified Psychoactive Substances.
  • Boundary with Unknown or Unspecified Psychoactive Substances-Induced Mental Disorders: Unknown or Unspecified Psychoactive Substances-Induced Mental Disorders can be associated with a single episode of unknown or unspecified psychoactive substances use. If a Unknown or Unspecified Psychoactive Substances-Induced Mental Disorder has occurred as a form of harm resulting from a single episode of unknown or unspecified psychoactive substances use, both Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances and the relevant Unknown or Unspecified Psychoactive Substances-Induced Mental Disorder should be diagnosed (e.g., Episode of Harmful Unknown or Unspecified Psychoactive Substances Use with Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substances).
  • Boundary with overdose: When ingestion of psychoactive substances results in symptoms of overdose (e.g., coma; life-threatening cardiac or respiratory suppression), a diagnosis from the grouping of Harmful Effects of Substances in the chapter on Injury, Poisoning or Certain Other Consequences of External Causes should also be assigned.
• 6C4G.1 Harmful pattern of use of unknown or unspecified psychoactive substance

  A pattern of use of an unknown or unspecified psychoactive substance that has caused damage to a person’s physical or mental health or has resulted in behaviour leading to harm to the health of others. The pattern of substance use is evident over a period of at least 12 months if use is episodic or at least one month if use is continuous (i.e., daily or almost daily). Harm to health of the individual occurs due to one or more of the following: (1) behaviour related to intoxication; (2) direct or secondary toxic effects on body organs and systems; or (3) a harmful route of administration. Harm to health of others includes any form of physical harm, including trauma, or mental disorder that is directly attributable to behaviour related to substance intoxication on the part of the person to whom the diagnosis of Harmful pattern of use of unknown or unspecified psychoactive substance applies. [1]

  Essential (Required) Features:

  • A pattern of continuous, recurrent, or sporadic use of unknown or unspecified psychoactive substances that has caused clinically significant damage to a person’s physical health or mental health (e.g., Unknown or Unspecified Psychoactive Substances-Induced Mood Disorder), or has resulted in behaviour leading to harm to the health of others.
  • Harm to health of the individual occurs due to one or more of the following: (1) behaviour related to intoxication; (2) direct or secondary toxic effects on body organs and systems; or (3) a harmful route of administration.
  • Harm to health of others includes any form of physical harm, including trauma, or mental disorder that is directly attributable to behaviour related to substance intoxication on the part of the person to whom the diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances applies.
  • The pattern of unknown or unspecified psychoactive substance use is evident over a period of at least 12 months if unknown or unspecified psychoactive substance use is episodic or at least 1 month if use is continuous.
  • Harm to health is not better accounted for by another medical condition or another mental disorder, including another Disorder Due to Substance Use (e.g., Substance Withdrawal).

  Note: Harm to the health of the person to whom the diagnosis applies includes injuries caused by behaviour related to intoxication (e.g., impulsive aggressive behaviour, psychomotor impairment leading to injury; acute health problems resulting from substance use (e.g., overdose, acute gastritis, the effects of hypoxia or prolonged hyperactivity or inactivity), and exacerbation or decompensation of pre-existing chronic health problems (e.g., hypertension, liver disease, or peptic ulceration). Harm may also result from a harmful route of administration (e.g., injecting drug use causing blood-borne virus infections, cocaine use causing a perforated nasal septum). The relevant diagnostic codes from other chapters of the ICD-11, including the chapter on Injury, Poisoning or Certain Other Consequences of External Causes, should be used to describe the specific health consequences of the harmful substance use.

  Harm to the health of others includes any form of physical harm, including trauma (e.g., impaired driving causing a motor vehicle accident, assaultive behaviour leading to bodily harm to another person) or mental disorder (e.g., Post-Traumatic Stress Disorder arising from an assault by the intoxicated individual) that is directly attributable to behaviour due to substance intoxication on the part of the person to whom the diagnosis of Harmful Pattern of Psychoactive Substance Use applies.

  Course Specifiers:

  A specifier is used to further describe the harmful pattern of substance use, using a fifth-digit code. The fourth-digit code indicates the substance class (i.e., G for unknown or unspecified psychoactive substances).

  6C4G.10 Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, episodic

  This category is assigned when all the diagnostic requirements for Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances are met and there is evidence of a pattern of recurrent episodic or intermittent use of unknown or unspecified psychoactive substances over a period of at least 12 months that has caused clinically significant harm to a person’s physical or mental health or has resulted in behaviour leading to harm to the health of others.

  6C4G.11 Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, continuous

  This category is assigned when all the diagnostic requirements for Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances are met and there is evidence of a pattern of continuous unknown or unspecified psychoactive substance use (daily or almost daily) over a period of at least 1 month that has caused clinically significant harm to a person’s physical or mental health or has resulted in behaviour leading to harm to the health of others.

  6C4G.1Z Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, unspecified

  Additional Clinical Features:

  • There must be explicit evidence of harm to the individual’s physical or mental health, or of related behaviour due to Unknown or Unspecified Psychoactive Substance Intoxication that has led to harm to the physical or mental health of others. There must also be a clear causal relationship between the harm to health and the episodic or continuous use of unknown or unspecified psychoactive substances.
  • The likelihood of harm to self or others due behaviour related to intoxication varies substantially by substance. For example, such behaviour is unlikely to arise from caffeine or nicotine intoxication.
  • As more information becomes available about symptoms and behaviours related to the pattern of unknown or unspecified psychoactive substance use as well as physiological features indicative of neuroadaptation to the substance, the diagnosis may be changed to Unknown or Unspecified Psychoactive Substance Dependence if diagnostic requirements are met.

  Boundary with Normality (Threshold):

  • The diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances requires clinically significant harm to the individual’s physical or mental health or that of others. Examples of impact on physical or mental health that would not be considered clinically significant include mild hangovers, brief episodes of vomiting, or transient depressed mood.
  • A pattern of unknown or unspecified psychoactive substance use may cause a range of problems in functioning (e.g., missed appointments, arguments with loved ones) that are not sufficiently severe to constitute clinically significant harm to physical or mental health. Such problems are not a sufficient basis for a diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances.

  Developmental Presentations:

  • Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances is often a characteristic of late adolescence and young adulthood, and injuries and the consequences of aggressive behaviour are particularly common in this age group.
  • Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances in older adults may cause injuries and fractures due to the combination of lowered tolerance, psychomotor impairment induced by a substance, and disorders associated with ageing such as osteoporosis and Dementia.

  Sex- and/or Gender-Related Features:

  • The prevalence of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances is higher in males than females, but the gender differential is smaller in countries where women play a greater role in the workforce. Gender differences in injuries and other forms of harm due to substance use are recognized.

  Boundaries with Other Disorders and Conditions (Differential Diagnosis):

  • Boundary with Hazardous Use of Unknown or Unspecified Psychoactive Substances: Hazardous Use of Unknown or Unspecified Psychoactive Substances is classified in the chapter on ‘Factors Influencing Health Status or Contact with Health Services’ in the ICD-11 and not in the chapter on Mental, Behavioural, and Neurodevelopmental Disorders. Hazardous Use of Unknown or Unspecified Psychoactive Substances appreciably increases the risk of harmful physical or mental health consequences to the user or to others to an extent that warrants attention and advice from health professionals, but has not resulted in specific identifiable harm and therefore does not meet the diagnostic requirements for Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances.
  • Boundary with Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances: If the harm to health is a result of a single episode of use rather than a pattern of substance use, whether episodic or continuous, a diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances should be assigned. Unknown or Unspecified Psychoactive Substance use is generally considered to be following a pattern if there has been at least episodic or intermittent use over a period of at least 12 months. If harm is caused by use of unknown or unspecified psychoactive substances but no information is available about the pattern or history of unknown or unspecified psychoactive substance use, a diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances may be assigned until such time as evidence for a pattern of use is ascertained.
  • Boundary with Unknown or Unspecified Psychoactive Substance Dependence: In Unknown or Unspecified Psychoactive Substance Dependence, individuals use unknown or unspecified psychoactive substances persistently despite harm and adverse consequences. Harm caused by such use may be similar to that observed in Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances. However, Unknown or Unspecified Psychoactive Substance Dependence also includes additional features of impaired ability to control use and increasing priority given to the substance use over other activities. Physiological features (e.g., tolerance) may also be present. If all diagnostic requirements for Unknown or Unspecified Psychoactive Substance Dependence are met, Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances should not be assigned.
  • Boundary with Unknown or Unspecified Psychoactive Substance Intoxication: Unknown or Unspecified Psychoactive Substance Intoxication is defined by unknown or unspecified psychoactive substance use that results in clinically significantly, transient unknown or unspecified psychoactive substance-specific symptoms. Recovery from Unknown or Unspecified Psychoactive Substance Intoxication is generally complete and absent of physical or mental sequelae. A pattern or repeated intoxication may or may not result in harm to a person’s physical or mental health or to the health of others. If there is continuing damage or harm as a result of repeated or continuous use of unknown or unspecified psychoactive substances, a diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances may be assigned. If relevant at the time of the clinical encounter (e.g., in an emergency room), Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances may be diagnosed with an associated diagnosis of Unknown or Unspecified Psychoactive Substance Intoxication.
  • Boundary with Unknown or Unspecified Psychoactive Substance Withdrawal: Unknown or Unspecified Psychoactive Substance Withdrawal occurs upon cessation or reduction of a substance in the context of physiological dependence or when unknown or unspecified psychoactive substances have been taken for a prolonged period or in large amounts. Some features of unknown or unspecified psychoactive substance withdrawal may include physical or mental harm (e.g., seizures, delusions, hallucinations, anxiety). If the symptoms are entirely explained by the Unknown or Unspecified Psychoactive Substance Withdrawal, an additional diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances is not warranted. However, if the symptoms substantially exceed the expected withdrawal syndrome in duration or type or severity and the diagnostic requirements for Unknown or Unspecified Psychoactive Substance Dependence are not met, Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances can be assigned as the primary diagnosis, with an associated diagnosis of Unknown or Unspecified Psychoactive Substance Withdrawal.
  • Boundary with Unknown or Unspecified Psychoactive Substance-Induced Mental Disorders: If a Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder has occurred as a form of harm resulting from a pattern of unknown or unspecified psychoactive substance use, both Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances and the relevant Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder should be diagnosed (e.g., Harmful Pattern of Unknown or Unspecified Psychoactive Substance Use with Anxiety Disorder induced by Unknown or Unspecified Psychoactive Substance).
  • Boundary with other mental disorders and other medical conditions: Numerous mental disorders as well as subthreshold symptoms may co-occur with episodic or continuous patterns of unknown or unspecified psychoactive substance use. Similarly, continuous or episodic unknown or unspecified psychoactive substance use increases the risk for mental disorders as well as other medical conditions. Co-occurring mental disorders and comorbid medical conditions should be diagnosed separately, along with a diagnosis of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances.
• 6C4G.2 Unknown or unspecified psychoactive substance dependence

  Unknown or unspecified psychoactive substance dependence is a disorder of regulation of use of an unknown or unspecified substance arising from repeated or continuous use of the substance. The characteristic feature is a strong internal drive to use the unknown or unspecified substance, which is manifested by impaired ability to control use, increasing priority given to use over other activities and persistence of use despite harm or negative consequences. These experiences are often accompanied by a subjective sensation of urge or craving to use the unknown or unspecified substance. The features of dependence are usually evident over a period of at least 12 months but the diagnosis may be made if use of the unknown or unspecified substance is continuous (daily or almost daily) for at least 3 months. [1]

  Essential (Required) Features:

  • A pattern of recurrent episodic or continuous use of unknown or unspecified psychoactive substances with evidence of impaired regulation of unknown or unspecified psychoactive substance use that is manifested by two or more of the following:
    • Impaired control over unknown or unspecified psychoactive substance use (i.e., onset, frequency, intensity, duration, termination, context);
    • Increasing precedence of unknown or unspecified psychoactive substance use over other aspects of life, including maintenance of health, and daily activities and responsibilities, such that unknown or unspecified psychoactive substance use continues or escalates despite the occurrence of harm or negative consequences (e.g., repeated relationship disruption, occupational or scholastic consequences, negative impact on health);
    • Physiological features indicative of neuroadaptation to the substance, including: 1) tolerance to the effects of unknown or unspecified psychoactive substances or a need to use increasing amounts of unknown or unspecified psychoactive substances to achieve the same effect; 2) withdrawal symptoms following cessation or reduction in use of unknown or unspecified psychoactive substances (see Unknown or Unspecified Psychoactive Substance Withdrawal), or 3) repeated use of unknown or unspecified psychoactive substances or pharmacologically similar substances to prevent or alleviate withdrawal symptoms. Physiological features are only applicable for certain substances.
  • The features of dependence are usually evident over a period of at least 12 months but the diagnosis may be made if use is continuous (daily or almost daily) for at least 3 months.

  Course Specifiers:

  A specifier is also used to describe the pattern of substance use in the context of Unknown or Unspecified Psychoactive Substance Dependence. Unlike alcohol, separate codes for continuous and episodic current use are not provided.

  6C4G.20 Unknown or Unspecified Psychoactive Substance Dependence, current use

  Current Unknown or Unspecified Psychoactive Substance Dependence with episodic or continuous use of unknown or unspecified psychoactive substances within the past month.

  6C4G.21 Unknown or Unspecified Psychoactive Substance Dependence, early full remission

  After a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence and often following a treatment episode or other intervention (including self-help intervention), the individual has been abstinent from unknown or unspecified psychoactive substances during a period lasting from between 1 and 12 months.

  6C4G.22 Unknown or Unspecified Psychoactive Substance Dependence, sustained partial remission

  After a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence, and often following a treatment episode or other intervention (including self-help intervention), there is a significant reduction in unknown or unspecified psychoactive substance use for more than 12 months, such that even though intermittent or continuous use has occurred during this period, the diagnostic requirements for dependence have not been met.

  6C4G.22 Unknown or Unspecified Psychoactive Substance Dependence, sustained full remission

  After a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence, and often following a treatment episode or other intervention (including self-intervention), the person has been abstinent from unknown or unspecified psychoactive substances for 12 months or longer.

  6C4G.2Z Unknown or Unspecified Psychoactive Substance Dependence, unspecified

  Additional Clinical Features:

  • A subjective sensation of urge or craving to use unknown or unspecified psychoactive substances often, but not always, accompanies the Essential Features of Unknown or Unspecified Psychoactive Substance Dependence.
  • When present as an aspect of Unknown or Unspecified Psychoactive Substance Dependence, withdrawal symptoms must be consistent with the known withdrawal state for unknown or unspecified psychoactive substances (see Unknown or Unspecified Psychoactive Substance Withdrawal). Onset and course of withdrawal are time-limited and are related to the type of substance and the dose used immediately before cessation or reduction in amount.
  • Tolerance varies as a function of individual factors (e.g., substance use history, genetics) and should be differentiated from initial levels of response during intoxication, which also exhibit significant individual variability. Laboratory testing that reveals high levels of the substance in bodily fluids with no evidence of significant symptoms of intoxication may be suggestive of tolerance. Tolerance to the effects to substances as indicated by different psychophysiological responses can develop at varying rates (e.g., tolerance to respiratory depression caused by opioid intoxication may develop prior to tolerance to the sedating effects of the drug). With abstinence, tolerance effects diminish over time.
  • Individuals with certain comorbid medical conditions (e.g., chronic liver disease) typically have reduced tolerances to substances.
  • Physical or mental health consequences (beyond the Essential Features of Substance Dependence) typically occur in persons with Substance Dependence but are not required for the diagnosis. Similarly, functional impairment in one or several domains of life (e.g., work, domestic responsibilities, child-rearing) is commonly seen in persons with Substance Dependence, but is not required in order to assign the diagnosis.
  • Individuals with Substance Dependence have elevated rates of many other mental disorders, including Conduct-Dissocial Disorder, Attention Deficit Hyperactivity Disorder, Impulse Control Disorders, Post-Traumatic Stress Disorder, Social Anxiety Disorder, Generalized Anxiety Disorder, Mood Disorders, Psychotic Disorders, and Personality Disorder with prominent dissocial features, as well as subthreshold symptoms. The specific pattern of co-occurrence depends on the specific substance involved, and reflects common risk factors and common causal pathways. These are distinguished from Substance-Induced Mental Disorders, in which the symptoms are a result of the direct physiological effects of the substance on the central nervous system.
  • A pattern of substance use that includes frequent or high dose administration occurs more often among certain subgroups (e.g., adolescents). In these cases, peer group dynamics may contribute to the maintenance of substance use. Regardless of the social contributions to the behaviour, a pattern of substance use that is consistent with subgroup norms should not be considered as presumptive evidence of Substance Dependence unless all diagnostic requirements for the disorder are met.

  Boundary with Normality (Threshold):

  • Frequent or even daily substance use of unknown or unspecified psychoactive substances does not automatically imply a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence. There must also be evidence of the Essential Features of Unknown or Unspecified Psychoactive Substance Dependence such as impaired control over use, increasing precedence of use over other life priorities, or physiological features.
  • The presence of physiological features such as tolerance and withdrawal is sometimes referred to as ‘physiological dependence’. These features may occur, for example, in response to prolonged therapeutic use of certain medications, such as in patients who are appropriately prescribed opioid analgesics for cancer pain. By themselves, however, these features are not sufficient for a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence, which also requires either impaired control over substance use or increasing precedence of unknown or unspecified psychoactive substance use over other activities.

  Course Features:

  • The course of Substance Dependence varies by substance, frequency, intensity, and duration of use. The central features of the dependence syndrome may be overshadowed by the harms to physical and mental health that patients with dependence often experience and for which they frequently seek treatment. Numerous medical conditions can occur due to substance use in the course of Substance Dependence. These conditions tend to be specific for each substance, although some are shared across substances. Negative consequences to physical health reflect either the known pharmacological effects of the relevant substance, the toxic effects of the substance on tissues and organs, or the route of administration (e.g., intravenous self-administration). Examples include alcoholic cirrhosis, infective endocarditis, and HIV/AIDS. Medical conditions caused by substance use should be diagnosed separately.

  Developmental Presentations:

  • Substance Dependence may develop more rapidly during adolescence than is usual during adulthood, especially when there are familial or other risk factors for Substance Dependence.
  • Tolerance to psychoactive substances may develop rapidly in adolescents and young adults, and decline equally rapidly when substance use ceases or is reduced in quantity or frequency.
  • Withdrawal symptoms are well recognized in neonates born to women with Substance Dependence who have used psychoactive substances during pregnancy. However, the presence of a withdrawal state in a neonate should not be the sole basis for a diagnosis of Substance Dependence in the mother.
  • Older adults often have reduced tolerance to substances.

  Sex- and/or Gender-Related Features:

  • Substance Dependence has similar features in men and women, although the intensity of substance use and duration of use necessary to result in dependence may differ by sex.
  • Women are less likely to be involved with the legal system in relation to substance use and therefore may be less likely to come to clinical attention than men. In clinical contexts, women may be reluctant to admit using substances due to prevailing social attitudes and proscriptions.
  • In some societies it may be culturally unacceptable for women to admit to substance use. Specific probing may be necessary to elicit a history of substance use and dependence.

  Boundaries with Other Disorders and with Normality:

  • Boundary with Unknown or Unspecified Psychoactive Substance Intoxication: Episodic or continuous intoxication with unknown or unspecified psychoactive substances is a typical feature of Unknown or Unspecified Psychoactive Substance Dependence, but is not an Essential Feature. Conversely, even if frequent and severe, Unknown or Unspecified Psychoactive Substance Intoxication alone is not a basis for a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence. If all diagnostic requirements of both conditions are met for the same episode of care, Unknown or Unspecified Psychoactive Substance Dependence should be assigned as the primary diagnosis, with an associated diagnosis of Unknown or Unspecified Psychoactive Substance Intoxication (e.g., Unknown or Unspecified Psychoactive Substance Dependence with Unknown or Unspecified Psychoactive Substance Intoxication) if appropriate to the specific clinical situation (e.g., in emergency settings).
  • Boundary with Harmful Use of Unknown or Unspecified Psychoactive Substances: Unknown or Unspecified Psychoactive Substance Dependence is often associated with physical and mental health consequences, such as those seen in Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances. In the absence of the Essential Features of Unknown or Unspecified Psychoactive Substance Dependence, a diagnosis of Harmful Use of Unknown or Unspecified Psychoactive Substances can be given when there has been demonstrable harm to the individual’s physical or mental health or that of others. Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances and Unknown or Unspecified Psychoactive Substance Dependence should not be diagnosed together.
  • Boundary with Unknown or Unspecified Psychoactive Substance Withdrawal: Many individuals with Unknown or Unspecified Psychoactive Substance Dependence develop Unknown or Unspecified Psychoactive Substance Withdrawal upon cessation or reduction in the amount of unknown or unspecified psychoactive substances consumed. In such cases, both Unknown or Unspecified Psychoactive Substance Dependence and Unknown or Unspecified Psychoactive Substance Withdrawal should be diagnosed. However, Unknown or Unspecified Psychoactive Substance Withdrawal can be diagnosed in the absence of a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence.
  • Boundary with Unknown or Unspecified Psychoactive Substance-Induced Mental Disorders: The impact of repeated or continuous use of substances characteristic of Unknown or Unspecified Psychoactive Substance Dependence may include Unknown or Unspecified Psychoactive Substance-Induced Mental Disorders, in which case both Unknown or Unspecified Psychoactive Substance Dependence and the relevant Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder should be diagnosed (e.g., Unknown or Unspecified Psychoactive Substance Dependence with Unknown or Unspecified Psychoactive Substance-Induced Delirium).
• 6C4G.3 Intoxication due to unknown or unspecified psychoactive substance

  Intoxication due to unknown or unspecified psychoactive substance is a transient condition that develops during or shortly after the administration of an unknown or unspecified psychoactive substance that is characterised by disturbances in level of consciousness, cognition, perception, affect or behaviour, or other psychophysiological functions and responses. This diagnosis should be made only when there is strong evidence that an unidentified substance has been taken and the features cannot be accounted for by another disorder or disease. [1]

  Essential (Required) Features:

  • Transient and clinically significant disturbances in consciousness, cognition, perception, affect, behaviour, or coordination that develop during or shortly after the consumption or administration of unknown or unspecified psychoactive substances.
  • The symptoms must be compatible with the known pharmacological effects of unknown or unspecified psychoactive substances, and their intensity is closely related to the amount of unknown or unspecified psychoactive substances consumed.
  • The symptoms of intoxication are time-limited and abate as unknown or unspecified psychoactive substances are cleared from the body.
  • Symptoms are not better accounted for by another medical condition (See below) or another mental disorder, including another Disorder Due to Substance Use (e.g., Withdrawal from a different substance).

  Examples of Medical Conditions That May Present with Symptoms Similar to Substance Intoxication

  • Head injury (with or without cerebral contusion or intracranial haemorrhage or haematoma)
  • Meningitis and encephalitis
  • Diabetic ketoacidosis or hypoglycaemia
  • Hepatic or other metabolic encephalopathy
  • Wernicke’s encephalopathy
  • Electrolyte disturbance
  • Hypoxia or hypercapnia
  • Systemic infection

  Severity of Intoxication Specifier:

  Depending on the specific clinical situation and the information available, Substance Intoxication may be classified according to the level of severity as mild, moderate, or severe. The level of intoxication is usually related to the dose, route of administration, half-life, and duration of action of the substance. Severity of intoxication is also affected by individual variability (e.g., differences in body weight, substance metabolism, or tolerance). Susceptibility to substance intoxication may also be greater in individuals with comorbid medical conditions affecting drug pharmacokinetics (e.g., renal or hepatic insufficiency).

  For some substances, there are specific tests for detecting and determining the concentration of substances in bodily fluids (e.g., blood, urine), which can be important tools for clinical management. However, severity of intoxication should be determined on the basis of clinical assessment, as specified below, and not solely based on the presence and level of the substance in bodily fluids.

  The level of medical attention that may be required in response to substance intoxication varies according to the severity of intoxication and the substance involved, and varies from precautionary observation to urgent intervention to prevent death or permanent harm (e.g., administration of antagonist treatment; intubation).

  The severity of intoxication is classified using the following Extension (X) Codes in addition to the appropriate intoxication category. Extension codes are attached to the category to which they apply using an ampersand (&).

  XS5W Mild

  Mild substance intoxication is a state in which there are clinically recognizable disturbances in psychophysiological functions and responses (e.g., motor coordination, attention and judgement) that vary by substance, but there is little or no disturbance in the level of consciousness.

  The code for Intoxication Due to Unknown or Unspecified Psychoactive Substance, mild is 6C4G.3&XS5W.

  XS0T Moderate

  Moderate substance intoxication is a state in which there are marked disturbances in psychophysiological functions and responses (e.g., motor coordination, attention and judgement) that vary by substance, with substantial impairment on tasks that require these functions. There is some disturbance in level of consciousness.

  The code for Intoxication Due to Unknown or Unspecified Psychoactive Substance, moderate is 6C4G.3&XS0T.

  XS25 Severe

  Severe substance intoxication is a state in which there are obvious disturbances in psychophysiological functions and responses (e.g., motor coordination, attention and judgement) that vary by substance, with marked disturbance in level of consciousness. There is severe impairment to the extent that the person may not be capable of self-care or self-protection, and may be unable to communicate or cooperate with assessment and intervention.

  The code for Intoxication Due to Unknown or Unspecified Psychoactive Substance, severe is 6C4G.3&XS25.

  Additional Clinical Features for Intoxication:

  • Psychoactive substances, whether of the same or a different pharmacological class, may interact such that they exacerbate or modify the features of intoxication. In cases of multiple psychoactive substance use in which more than one specific substance can be identified as a cause of the intoxication, it is recommended that the corresponding specific Substance Intoxication categories for each relevant substance be assigned (e.g., 6C40.3 Alcohol Intoxication and 6C4E.3 Intoxication Due to Unknown or Unspecified Psychoactive Substance) rather than 6C4F.3 Intoxication Due to Unknown or Unspecified Psychoactive Substances.
  • Intoxication Due to Unknown or Unspecified Psychoactive Substance may occur in the presence of medical conditions that cause impairment of levels of consciousness, cognition, perception, affect, behaviour, or coordination, which should be diagnosed separately. Determination of the aetiology of the disturbances in psychophysiological functions or responses may require longitudinal assessment.
  • A diagnosis of Intoxication Due to Unknown or Unspecified Psychoactive Substance can be assigned if the substance consumed is initially unknown to the clinician. As more information becomes available (e.g., laboratory results, report from a collateral informant) the diagnosis should be changed to indicate the substance responsible for intoxication.

  Boundary with Normality (Threshold):

  • Measurement of the presence or concentration of a substance in breath, blood, saliva, urine or other body fluids may be an important tool in the clinical management of Substance Intoxication. However, detection of a psychoactive substance in body fluids does not constitute a presumptive diagnosis of Substance Intoxication.

  Course Features:

  • The onset of Substance Intoxication varies according to the route of administration, the absorption of the substance and other pharmacokinetic factors. Generally, inhalation (smoking) and intravenous injecting routes lead to more rapid onset of intoxication, though oral ingestion may also lead to intoxication within minutes, depending on the substance.
  • Substance Intoxication is a transient condition, with the duration of intoxication depending on multiple factors including: (1) the dose of the substance taken, (2) the half-life and duration of action of the particular substance, and (3) the formulation of the substance taken (e.g., for pharmaceutical preparations, whether a controlled-release drug has been taken). Intoxication may last from a few minutes up to several days following the episode of use. The intensity of intoxication lessens with time after reaching a peak of absorption, and the effects eventually disappear in the absence of further use of the substance.

  Culture-Related Features:

  • The degree and characteristics of intoxication displayed for a given amount of a psychoactive substance varies considerably with circumstances, with beliefs and expectations about the effects of the substance, and with the cultural acceptability of displaying these effects. These factors result in cultural differences in the extent and manifestations of intoxication.
  • There are also genetic differences in susceptibility to intoxication with specific psychoactive substances associated with certain ethnic groups. Cultural and ethnically linked genetic factors have been better documented for alcohol than for other substances.

  Developmental Presentations:

  • Naïve users including adolescents can show features of intoxication at lower levels of use, reflecting lower physical and learned tolerance.
  • Older adults may have a lower tolerance than younger people to the effects of substances.

  Sex- and/or Gender-Related Features:

  • The amount of substance and duration of use necessary to cause intoxication differs by sex, reflecting differences in body weight and composition.
  • Behaviour while intoxicated may vary by gender, reflecting not only physiological differences, but also cultural differences and role expectations.

  Boundaries with Other Disorders and Conditions (Differential Diagnosis):

  • Boundary with Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances and Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances: In Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances and Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, consumption or administration of unknown or unspecified psychoactive substances results in damage to the person’s physical or mental health (including a Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder) or in behaviour leading to harm to the health of others. Recovery from Intoxication Due to Unknown or Unspecified Psychoactive Substance is generally complete. Complications due to such effects of intoxication such as injury, the effects of prolonged hyperactivity or inactivity, or other tissue damage should be diagnosed as Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances or Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, as appropriate. If relevant at the time of the clinical encounter (e.g., in emergency settings), Intoxication Due to Unknown or Unspecified Psychoactive Substance can be given as an associated diagnosis, with Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances or Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances as the primary diagnosis.
  • Boundary with Unknown or Unspecified Psychoactive Substance Dependence: Episodic or continuous intoxication with unknown or unspecified psychoactive substances is a typical feature of Unknown or Unspecified Psychoactive Substance Dependence. If all diagnostic requirements of both conditions are met for the same episode of care, Unknown or Unspecified Psychoactive Substance Dependence should be assigned as the primary diagnosis, with an associated diagnosis of Intoxication Due to Unknown or Unspecified Psychoactive Substance.
  • Boundary with Unknown or Unspecified Psychoactive Substance Withdrawal: Unknown or Unspecified Psychoactive Substance Withdrawal occurs upon cessation or reduction of unknown or unspecified psychoactive substances in the context of physiological dependence or when unknown or unspecified psychoactive substances have been taken for a prolonged period or in large amounts. In contrast, the onset of Intoxication Due to Unknown or Unspecified Psychoactive Substance occurs immediately or shortly after the consumption of unknown or unspecified psychoactive substances. Moreover, intoxication and withdrawal syndromes for psychoactive substances are typically quite distinct.
  • Boundary with Unknown or Unspecified Psychoactive Substance-Induced Delirium: Delirium is characterized by disturbances in attention, orientation, and awareness that develop within a short period of time with symptoms that are transient and may fluctuate depending on the underlying aetiology. Delirium often includes disturbance of behaviour and emotion, and may include impairment in multiple cognitive domains. Disturbance of the sleep-wake cycle may also be present. Delirium can be caused by intoxication or withdrawal from substances. When symptoms of Delirium are attributable to Intoxication Due to Unknown or Unspecified Psychoactive Substance, an associated diagnosis of Unknown or Unspecified Psychoactive Substance-Induced Delirium should be assigned in addition to the diagnosis of Intoxication Due to Unknown or Unspecified Psychoactive Substance.
  • Boundary with other Unknown or Unspecified Psychoactive Substance-Induced Mental Disorders: Mental or behavioural symptoms that arise during Intoxication Due to Unknown or Unspecified Psychoactive Substance should only be used as a basis for diagnosing a Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder if the intensity or duration of the symptoms is substantially in excess of those that are characteristic of Intoxication Due to Unknown or Unspecified Psychoactive Substance and the symptoms are sufficiently severe to warrant specific clinical attention.
  • Boundary with other medical conditions: A variety of medical conditions may produce symptoms that are similar to those of Intoxication Due to Unknown or Unspecified Psychoactive Substance. Some of these medical conditions are life-threatening requiring immediate intervention. Evidence of unknown or unspecified psychoactive substance use (e.g., positive laboratory results) does not rule out the possibility of a comorbid medical condition. These alternative diagnoses must be considered in assessing Intoxication Due to Unknown or Unspecified Psychoactive Substance. Certain medical conditions may also augment or prolong the duration of intoxication. Symptoms of intoxication that persist after they can no longer be reasonably attributed to the pharmacological effects of unknown or unspecified psychoactive substances may suggest the presence of another medical condition. If it is determined that Intoxication Due to Unknown or Unspecified Psychoactive Substance is comorbid with a medical condition, both diagnoses should be assigned.
  • Boundary with overdose: When consumption or administration of psychoactive substances results in symptoms of overdose (e.g., coma; life-threatening cardiac or respiratory suppression), it is typically more appropriate to apply a diagnosis from the grouping of Harmful Effects of Substances in the chapter on Injury, Poisoning or Certain Other Consequences of External Causes rather than Substance Intoxication.
• 6C4G.4 Withdrawal due to unknown or unspecified psychoactive substance

  Withdrawal due to unknown or unspecified psychoactive substance is a clinically significant cluster of symptoms, behaviours and/or physiological features, varying in degree of severity and duration, that occurs upon cessation or reduction of use of an unknown or unspecified substance in individuals who have developed dependence or have used the unknown or unspecified substance for a prolonged period or in large amounts. Withdrawal due to unknown or unspecified psychoactive substance can also occur when prescribed psychoactive medications have been used in standard therapeutic doses. The specific features of the withdrawal state depend on the pharmacological properties of the unknown or unspecified substance. [1]

  Essential (Required) Features:

  • The presence of a clinically significant cluster of symptoms, behaviours, and/or physiological features that occurs upon cessation or reduction in the use of unknown or unspecified psychoactive substances in individuals who have developed dependence on unknown or unspecified psychoactive substances or have used unknown or unspecified psychoactive substances for a prolonged period or in large amounts.
  • The symptoms are not better accounted for by another medical condition or another mental disorder.

  Specifiers for clinical presentation:

  Because of clinically important variation in their withdrawal syndromes, the following specifiers can be applied to Unspecified (6C4G.4) Psychoactive Substance Categories.

  6C4G.40 Withdrawal due to Unknown or Unspecified Psychoactive Substance, uncomplicated

  All diagnostic requirements for Withdrawal due to Unknown or Unspecified Psychoactive Substance are met and the withdrawal state is not accompanied by perceptual disturbances or seizures.

  6C4G.41 Withdrawal due to Unknown or Unspecified Psychoactive Substance, with perceptual disturbances

  All diagnostic requirements for Withdrawal due to Unknown or Unspecified Psychoactive Substance are met and the withdrawal state is accompanied by perceptual disturbances (e.g., visual or tactile hallucinations or illusions) with intact reality testing. There is no evidence of confusion and other diagnostic requirements for Delirium are not met. The withdrawal state is not accompanied by seizures.

  6C4G.42 Withdrawal due to Unknown or Unspecified Psychoactive Substance, with seizures

  All diagnostic requirements for Withdrawal due to Unknown or Unspecified Psychoactive Substance are met and the withdrawal state is accompanied by seizures (i.e., generalized tonic-clonic seizures) but not by perceptual disturbances.

  6C4G.43 Withdrawal due to Unknown or Unspecified Psychoactive Substance, with perceptual disturbances and seizures

  All diagnostic requirements for Withdrawal due to Unknown or Unspecified Psychoactive Substance are met and the withdrawal state is accompanied by both seizures (i.e., generalized tonic-clonic seizures) and perceptual disturbances (e.g., visual or tactile hallucinations or illusions) with intact reality testing. Diagnostic requirements for Delirium are not met.

  6C4G.4Z Withdrawal due to Unknown or Unspecified Psychoactive Substance, unspecified

  Additional Clinical Features:

  • For some substances, characteristic features of Withdrawal due to Unknown or Unspecified Psychoactive Substance are opposite to the acute pharmacological effects of unknown or unspecified psychoactive substances.
  • Withdrawal due to Unknown or Unspecified Psychoactive Substance symptoms become more severe with repeated episodes of withdrawal (termed ‘kindling’), with aging, or in the presence of comorbid medical conditions.
  • A diagnosis of Withdrawal due to Unknown or Unspecified Psychoactive Substance can be assigned if the substance consumed is initially unknown. As more information becomes available (e.g., laboratory results, report from a collateral informant) the diagnosis should be changed to indicate the substance responsible for the withdrawal symptoms.

  Boundary with Normality (Threshold):

  • Withdrawal due to Unknown or Unspecified Psychoactive Substance should only be diagnosed when symptoms are consistent with those recognized as occurring upon cessation or reduction in use of unknown or unspecified psychoactive substances. Recent cessation or reduction of use and the presence of various non-specific transient symptoms is not sufficient to make the diagnosis of Withdrawal due to Unknown or Unspecified Psychoactive Substance.
  • Withdrawal symptoms should be differentiated from the transient physiological aftereffects of intoxication (‘hangover effect’).
  • Some individuals who have previously had Unknown or Unspecified Psychoactive Substance Dependence may experience symptoms similar to those of Withdrawal due to Unknown or Unspecified Psychoactive Substance months after the last use of the substance, particularly when the individual encounters stimuli (e.g., drug paraphernalia) and contexts (e.g., location where use was frequent) previously associated with past unknown or unspecified psychoactive substance use. These symptoms are more transient than those observed during Withdrawal due to Unknown or Unspecified Psychoactive Substance and occur exclusively when in contact with associated stimuli and contexts. A diagnosis of Withdrawal due to Unknown or Unspecified Psychoactive Substance should not be assigned under these circumstances.

  Course Features:

  • Withdrawal due to Unknown or Unspecified Psychoactive Substance is time-limited. Factors that influence the features and time course of Withdrawal due to Unknown or Unspecified Psychoactive Substance include: (1) the severity of Unknown or Unspecified Psychoactive Substance Dependence, if present, (2) the dose, frequency of use, and duration of unknown or unspecified psychoactive substance use prior to cessation or reduction of that use, (3) the half-life and duration of action of unknown or unspecified psychoactive substances, and (4) the presence of comorbid medical conditions (e.g., metabolic disturbances).

  Culture-Related Features:

  • Symptoms of withdrawal depend largely on the psychotropic characteristics of unknown or unspecified psychoactive substances. However, specific cultures may emphasize certain symptoms of withdrawal over others, making it more difficult to conduct a differential diagnosis. In addition, vernacular terms for withdrawal vary greatly.

  Boundaries with Other Disorders and Conditions (Differential Diagnosis):

  • Boundary with Unknown or Unspecified Psychoactive Substance Dependence: Many individuals with Unknown or Unspecified Psychoactive Substance Dependence develop Withdrawal due to Unknown or Unspecified Psychoactive Substance upon cessation or reduction in the amount of the substance. In such cases, both Unknown or Unspecified Psychoactive Substance Dependence and Withdrawal due to Unknown or Unspecified Psychoactive Substance should be diagnosed. However, Withdrawal due to Unknown or Unspecified Psychoactive Substance can be diagnosed in the absence of a diagnosis of Unknown or Unspecified Psychoactive Substance Dependence.
  • Boundary with Unknown or Unspecified Psychoactive Substance Intoxication: The onset of Unknown or Unspecified Psychoactive Substance Intoxication occurs immediately or shortly after the consumption of unknown or unspecified psychoactive substances. In contrast, Withdrawal due to Unknown or Unspecified Psychoactive Substance occurs upon cessation or reduction in the amount of unknown or unspecified psychoactive substances in the context of Unknown or Unspecified Psychoactive Substance Dependence or when unknown or unspecified psychoactive substances have been taken for a prolonged period or in large amounts. For unknown or unspecified psychoactive substances, the intoxication and withdrawal syndromes are typically distinct.
  • Boundary with Unknown or Unspecified Psychoactive Substance-Induced Delirium: Delirium is characterized by disturbances in attention, orientation, and awareness that develop within a short period of time with symptoms that are transient and may fluctuate depending on the underlying etiology. Delirium often includes disturbance of behaviour and emotion, and may include impairment in multiple cognitive domains. Disturbance of the sleep-wake cycle may also be present. Delirium may occur as an aspect of Withdrawal due to Unknown or Unspecified Psychoactive Substance, particularly during later stages of withdrawal. In such cases, diagnoses of both Substance Withdrawal and Unknown or Unspecified Psychoactive Substance-Induced Delirium should be assigned.
  • Boundary with other Unknown or Unspecified Psychoactive Substance-Induced Mental Disorders: Mental or behavioural symptoms that arise during Withdrawal due to Unknown or Unspecified Psychoactive Substance should only be used as a basis for diagnosing a Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder if the intensity or duration of the symptoms is substantially in excess of those that are characteristic of the Withdrawal due to Unknown or Unspecified Psychoactive Substance and the symptoms are sufficiently severe to warrant specific clinical attention. In such cases, if the withdrawal syndrome is ongoing, diagnoses of both Withdrawal due to Unknown or Unspecified Psychoactive Substance and a Unknown or Unspecified Psychoactive Substance-Induced Mental Disorder may be assigned.
  • Boundary with other mental disorders: Various symptoms associated with Withdrawal due to Unknown or Unspecified Psychoactive Substance overlap with those that are characteristic of other mental disorders (e.g., depressive and anxiety symptoms). Symptoms of Withdrawal due to Unknown or Unspecified Psychoactive Substance occur in specific temporal relationship to the cessation of use of unknown or unspecified psychoactive substances and diminish with the passage of time. Evidence supporting a mental disorder diagnosis would include the symptoms preceding the onset of unknown or unspecified psychoactive substance use, the symptoms persisting for a substantial period of time after cessation of unknown or unspecified psychoactive substances or withdrawal (e.g., 1 month or more, depending on the substance), or other evidence of a pre-existing mental disorder (e.g., a history of prior episodes not associated with unknown or unspecified psychoactive substance use).
  • Boundary with other medical conditions: It may be difficult to distinguish between various symptoms associated with Withdrawal due to Unknown or Unspecified Psychoactive Substance (e.g., nausea, retching or vomiting, seizures, abdominal cramps, diarrhea, perspiration, postural hypotension, decreased or increased heart rate, cough, sleep disruption) and those that are characteristic of other medical conditions. Symptoms of Withdrawal due to Unknown or Unspecified Psychoactive Substance occur in specific temporal relationship to the cessation of use of unknown or unspecified psychoactive substances and diminish with the passage of time.
  • Boundary with Foetus or Newborn Affected by Maternal Use of Tobacco, Alcohol, or Other Drugs of Addiction: The ICD-11 chapter on Certain Conditions Arising During the Perinatal Period contains categories for ‘Foetus or newborn affected by maternal use of tobacco, alcohol, and other drugs.’ A neonate exhibiting signs of Withdrawal due to Unknown or Unspecified Psychoactive Substance may also be Withdrawal due to Unknown or Unspecified Psychoactive Substance diagnosis in order to guide treatment together with appropriate diagnosis from the chapter on Certain Conditions Originating in the Perinatal Period.
• 6C4G.5 Delirium induced by unknown or unspecified psychoactive substance

  Delirium induced by unknown or unspecified psychoactive substance is characterised by an acute state of disturbed attention and awareness with specific features of delirium that develops during or soon after substance intoxication or withdrawal or during the use of an unknown or unspecified substance. The symptoms are not better explained by a primary mental disorder, by use of or withdrawal from another substance, or by another health condition that is not classified under Mental, behavioural and neurodevelopmental disorders. [1]

• 6C4G.6 Psychotic disorder induced by unknown or unspecified psychoactive substance

  Psychotic disorder induced by unknown or unspecified psychoactive substance is characterised by psychotic symptoms (e.g., delusions, hallucinations, disorganised thinking, grossly disorganised behaviour) that develop during or soon after intoxication with or withdrawal from an unknown or unspecified psychoactive substance. The symptoms are not better explained by a primary mental disorder (e.g., Schizophrenia, a Mood disorder with psychotic symptoms), as might be the case if the psychotic symptoms preceded the onset of the use of the unknown or unspecified psychoactive substance, if the symptoms persist for a substantial period of time after cessation of the use of the unknown or unspecified psychoactive substance or withdrawal from the unknown or unspecified psychoactive substance, or if there is other evidence of a pre-existing primary mental disorder with psychotic symptoms (e.g., a history of prior episodes not associated with the use of the unknown or unspecified psychoactive substance). [1]

  Essential (Required) Features:

  • The presentation is characterized by psychotic symptoms (e.g., delusions, hallucinations, or disorganized thinking or behaviour) that develop during or soon after intoxication with or withdrawal from unknown or unspecified psychoactive substances.
  • The intensity or duration of the psychotic symptoms is substantially in excess of psychotic-like disturbances of perception, cognition, or behaviour that are characteristic of Unknown or Unspecified Psychoactive Substance Intoxication or Unknown or Unspecified Psychoactive Substance Withdrawal.
  • The symptoms are not better accounted for by another mental disorder such as Schizophrenia or a Mood Disorder with psychotic symptoms. Evidence supporting a diagnosis of another mental disorder would include psychotic symptoms preceding the onset of unknown or unspecified psychoactive substance use, the symptoms persisting for a substantial period of time after cessation of unknown or unspecified psychoactive substance use or withdrawal (e.g., 1 month or more), or other evidence of a pre-existing mental disorder with psychotic symptoms (e.g., a history of prior episodes not associated with unknown or unspecified psychoactive substance use).
  • The symptoms are not a manifestation of another medical condition.
  • The symptoms cause significant distress or significant impairment in personal, family, social, educational, occupational or other important areas of functioning.

  When making a diagnosis of Psychotic Disorder induced by Unknown or Unspecified Psychoactive Substance, an additional diagnosis indicating the related pattern of unknown or unspecified psychoactive substance use should also be assigned. These include Episode of Harmful Use of Unknown or Unspecified Psychoactive Substance, Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substance, and Unknown or Unspecified Psychoactive Substance Dependence. A diagnosis of Unknown or Unspecified Psychoactive Substance Intoxication or Unknown or Unspecified Psychoactive Substance Withdrawal may also be assigned if applicable.

  Additional Clinical Features:

  • Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance may present with varying patterns of symptoms, depending on the specific substance used, that vary according to the characteristics of the user (e.g., genetics, metabolism, personality factors). Unknown or Unspecified Psychoactive Substance use in higher amounts or over longer periods of time is more likely to be associated with the development of a Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance.
  • Symptoms of Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance usually resolve or improve after sustained cessation of unknown or unspecified psychoactive substance use.
  • The duration of Substance Withdrawal for some substances can be protracted. For substances with more protracted withdrawal periods, the onset of symptoms of Substance-Induced Psychotic Disorder can occur up to several weeks after the cessation of substance use. Substance-Induced Psychotic Disorder symptoms related to substances with more protracted withdrawal periods may also last for correspondingly longer periods of time.
  • In cases in which multiple psychoactive substance are used, it is often challenging to distinguish which substance is the cause of the Substance-Induced Psychotic Disorder. When the specific etiological substance cannot be determined, a diagnosis of Substance-Induced Psychotic Disorder Due to Multiple Specified Psychoactive Substances including Medications may assigned. In cases of multiple psychoactive substance use in which more than one specific substance can be identified as a cause of the Substance-Induced Psychotic Disorder, the corresponding specific Substance-Induced Psychotic Disorder diagnoses should be given instead.

  Boundary with Normality (Threshold):

  • Symptoms of Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substances should be differentiated from known side effects of psychoactive medication that are not significantly impairing or distressing and from transient physiological aftereffects of intoxication (‘hangover effect’). The duration or severity of the symptoms in Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substances must be in excess of side effects (e.g., transient jitteriness as a side effect of methylphenidate) or ‘hangover effects’ (e.g., transient low mood following alcohol use) of Unknown or Unspecified Psychoactive Substances and result in significant distress or impairment of functioning.

  Boundaries with Other Disorders and Conditions (Differential Diagnosis):

  • Boundary with Unknown or Unspecified Psychoactive Substance Intoxication and Unknown or Unspecified Psychoactive Substance Withdrawal: Mental or behavioural symptoms that occur during Unknown or Unspecified Psychoactive Substance Intoxication or Unknown or Unspecified Psychoactive Substance Withdrawal should only be used as a basis for diagnosing a Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance if the intensity or duration of the symptoms is substantially in excess of those that are characteristic of Unknown or Unspecified Psychoactive Substance Intoxication or Unknown or Unspecified Psychoactive Substance Withdrawal and the symptoms are sufficiently severe to warrant specific clinical attention.
  • Boundary with Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances, Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, or Unknown or Unspecified Psychoactive Substance Dependence: The impact of repeated or continuous use of unknown or unspecified psychoactive substances characteristic of Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances and Unknown or Unspecified Psychoactive Substance Dependence may include Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance. Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substances can also be associated with a single episode of unknown or unspecified psychoactive substance use. In such cases, a Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance should be diagnosed together with a primary diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances, Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, or Unknown or Unspecified Psychoactive Substance Dependence.
  • Boundary with mental disorders not induced by unknown or unspecified psychoactive substances: Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substances are differentiated from mental disorders with similar features that are not induced by unknown or unspecified psychoactive substances on the basis of their onset, course and clinical features. A diagnosis of Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance requires evidence from history, physical or mental examination, or laboratory findings of recent unknown or unspecified psychoactive substance use, intoxication or withdrawal. Most Unknown or Unspecified Psychoactive Substance-Induced Mental Disorders resolve or improve within several weeks of cessation of unknown or unspecified psychoactive substance use. Mental disorders not induced by unknown or unspecified psychoactive substances may precede the onset of unknown or unspecified psychoactive substance use or may continue to be symptomatic during periods of sustained abstinence. The co-occurrence of unknown or unspecified psychoactive substance use or withdrawal and onset of symptoms of mental disorders should not be taken as evidence for a presumptive diagnosis of a Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance. Some people use substances to suppress symptoms of mental disorders (e.g., Schizophrenia and Other Primary Psychotic Disorders, Mood Disorders, Anxiety and Fear-Related Disorders, Personality Disorders) and full symptomatic presentations only emerge upon cessation or reduction in substance use. Furthermore, unknown or unspecified psychoactive substance use can exacerbate symptoms or precipitate an episode of a pre-existing mental disorder. Finally, unknown or unspecified psychoactive substance use may be associated with but not aetiologic for new onset of symptoms of a mental disorder. Although a diagnosis of a Psychotic Disorder Induced by Unknown or Unspecified Psychoactive Substance should not be assigned under these circumstances, an additional diagnosis of Episode of Harmful Use of Unknown or Unspecified Psychoactive Substances, Harmful Pattern of Use of Unknown or Unspecified Psychoactive Substances, or Unknown or Unspecified Psychoactive Substance Dependence may still be appropriate.
• 6C4G.7 Certain unknown or unspecified psychoactive substance-induced mental or behavioural disorders

References

1. World Health Organization. International Classification of Diseases, 11th Revision, for Mortality and Morbidity Statistics (ICD-11 MMS), 2026-01 release. World Health Organization; 2026.
2. World Health Organization. Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders (CDDR). World Health Organization; 2024.

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