Mental and Behavioural Disorders Due to Multiple Drug Use (F19)
DSM-5-TR: Other (or Unknown) Substance Use Disorder
ICD-10-AM and DSM-5-TR may classify conditions differently. Refer to APA and WHO for complete diagnostic criteria.
Key Facts
ICD-10 Range
F10-F19
Subcodes
5 subcodes
Australian Prevalence
Polysubstance use is common among Australian drug users presenting to treatment services. Methamphetamine combined with cannabis is the most frequent polysubstance pattern.
Global Prevalence
Polysubstance use is increasingly common worldwide, particularly combinations involving alcohol, cannabis, and stimulants.
Duration Requirement
As per individual substance categories (F10-F18)
Overview
This category is used when the substance use involves two or more psychoactive substances and it is not possible to determine which substance is most responsible for the disorder. This includes disorders arising from chaotic drug use or when substances from other categories (F11–F18) are mixed.
Diagnostic Criteria (ICD-10)
Core Features
- Use of two or more psychoactive substances
- Not possible to determine which substance is primarily responsible
- Pattern of chaotic or indiscriminate drug use
- Clinical features may include any combination of intoxication, dependence, withdrawal, or psychosis
Duration
As per individual substance categories (F10-F18)
Exclusion Criteria
- Disorder attributable to a single identified substance (use F10-F18)
ICD-10-AM Subcodes
| Code | Name | Description |
|---|---|---|
| F19.0 | Acute intoxication | |
| F19.1 | Harmful use | |
| F19.2 | Dependence syndrome | |
| F19.3 | Withdrawal state | |
| F19.5 | Psychotic disorder |
Classification Boundaries
Includes
- Multiple drug use NOS
- Multiple drug abuse
Australian Clinical Context
Polysubstance use is common among Australian drug users presenting to treatment services. The AIHW National Drug Strategy Household Survey monitors patterns. Treatment often involves integrated care addressing multiple substance dependencies simultaneously.
Medicare (MBS) Pathways
Better Access to Mental Health Care
The primary Medicare pathway for mental health treatment in Australia. Requires a GP Mental Health Treatment Plan (MHTP) referral. Available for any clinically diagnosed mental disorder.
| Provider Type | MBS Items | Session Type |
|---|---|---|
| Clinical Psychologist | 80000–80025 | Psychological therapy (higher rebate) |
| Registered Psychologist | 80100–80123 | Focused psychological strategies |
| Occupational Therapist | 80125–80145 | Focused psychological strategies |
| Social Worker | 80150–80175 | Focused psychological strategies |
| Psychiatrist | 291, 296–299, 300–308 | Psychiatric consultation |
Clinical Psychologist
Registered Psychologist
Occupational Therapist
Social Worker
GP referral items: 2700, 2701, 2715, 2717
Eligibility: Any clinically diagnosed mental disorder as defined by WHO ICD-10 Chapter V. Requires a GP or psychiatrist referral.
Exclusions:
- Intellectual disability (use Complex Neurodevelopmental Disorder pathway or specialist referral)
- Dementia and organic mental disorders (use specialist referral pathway)
- Tobacco use disorder
State and territory drug and alcohol services may also apply alongside MBS. Complex presentations may require specialist coordination.
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Reference information sourced from MBS Online (mbsonline.gov.au). Item availability, rebates, and eligibility criteria may change. This is not billing advice — always verify current items before claiming. Last verified: April 2026.
Clinical Documentation Notes
When coding polysubstance use, if a primary substance can be identified, code under the specific substance category (F10–F18). F19 should only be used when the pattern is genuinely mixed and no single substance predominates. Document all substances used, including quantities and routes of administration.
Related Assessment Tools
Related Clinical Calculators
Other validated instruments commonly used alongside the Mental and Behavioural Disorders Due to Multiple Drug Use (F19).
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Related Diagnostic Codes
ICD-10-AM diagnostic codes commonly associated with the Mental and Behavioural Disorders Due to Multiple Drug Use (F19).
Frequently Asked Questions
References
- World Health Organization. ICD-10-AM.
- AIHW. National Drug Strategy Household Survey.
- American Psychiatric Association. DSM-5-TR. 2022.
Clinical Scoring Calculator — Not a Diagnostic Tool
This tool calculates scores based on published guidelines for professional reference. It does not provide clinical diagnoses. Scores are provided as reference information only and should be interpreted by a qualified practitioner in the context of a comprehensive assessment.
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