ICD-11 classification of substance use

The ICD-11 terms used in these guidelines to describe the spectrum of substance use are ‘hazardous use’, ‘harmful use’ and ‘substance dependence’; for criteria, see Terminology describing the spectrum of substance use. The hierarchy of escalating use is represented in ICD-11 classifications of substance use, gambling and gaming.
Table 1. Terminology describing the spectrum of substance use

World Health Organization (WHO), 2022

Hazardous use

Substance use increases risk of physical or mental harm to the person or others through its frequency, the amount used, the method of ingestion, associated behaviours or a combination of these.

Harmful use

Substance use has damaged the physical or mental health of the person or others. This term is used in these guidelines to include a single episode or a pattern of harmful use.

Substance dependence

Substance use is recurrent and episodic or continuous, with 2 or more of the following features [NB1] [NB2]:

  • impaired control of use (onset, frequency, intensity, duration, termination, context of use)
  • use continues or escalates despite harms or negative consequences on other aspects of life (eg disruption in relationships, work, school, health)
  • physiological features are present, including tolerance [NB3], withdrawal, or repeated use to prevent or alleviate withdrawal symptoms [NB4].
Note:

NB1: Features of substance dependence are usually evident over at least 12 months, but the diagnosis may be made if use is daily or almost daily for 3 months.

NB2: For comparison, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) defines substance use disorder as the presence of at least 2 of a set of 11 criteria, as described in Hasin DS, O’Brien CP, Auriacombe M, Borges G, Bucholz K, Budney A, et al. DSM-5 criteria for substance use disorders: recommendations and rationale. Am J Psychiatry 2013;170(8):834-51 URL.

NB3: Tolerance is a decreased response to a substance over repeated or prolonged exposurePietrzykowski, 2008.

NB4: Withdrawal symptoms occur with stopping or reducing substance useWorld Health Organization (WHO), 2022.

Each of these diagnoses (hazardous use, harmful use or substance dependence) can apply to use of any psychoactive substance, regardless of its legal status. Each can occur with the use of medications as prescribed, or with nonmedical use. Nonmedical use describes the use of medications that does not align with the directed use; for example, use in order to become intoxicated or to treat a symptom other than the clinician intendedAustralian Institute of Health and Welfare (AIHW)McNeely, 2014.

Note: Nonmedical use describes the use of medications that does not align with the directions of the clinician.