People may seek alcohol and other drug (AOD) treatment services for use of one or several substances (including alcohol). The principal drug of concern (PDOC) is the main substance that the client stated led them to seek treatment. Clients can also nominate up to 5 additional drugs of concern, though these are not necessarily the subject of any treatment within the episode.
This section presents information on treatment episodes provided to clients for their own AOD use only. It is assumed that only the person using a substance themselves can accurately report their principal drug of concern. Therefore, these data are not collected for people who are seeking treatment for someone else’s drug use.
This section focuses on treatment episodes provided for alcohol, amphetamines, cannabis and heroin as the PDOC. These 4 drugs were consistently the most common principal drugs of concern across Australia in the 10-year period up to 2020–21. For detailed information on each drug of concern, refer to the technical notes.
Key findings
In 2020–21:
- The most common principal drug of concern was alcohol (37% of episodes), followed by amphetamines (24%), cannabis (19%) and heroin (4.6%).
- Around 4 in 5 treatment episodes for amphetamines were for methamphetamine as the principal drug of concern (79% or 42,700 episodes).
Over the 10-year period to 2020–21:
- The top 4 principal drugs of concern remained consistent over the 10 years to 2020–21, with amphetamines replacing cannabis as the second most common principal drug of concern from 2015–16.
- While the number of treatment episodes for alcohol as the principal drug of concern increased from 67,400 to 83,600 over this period, proportionally, treatment episodes for alcohol (in relation to all drugs) decreased from 46% to 37%.
- Treatment episodes for amphetamines increased by 220% since 2011–12 (16,900 to 54,300), although this has declined since 2019–20 (61,000).
- Treatment episodes for heroin fell from 8.8% to 6.1% (or 12,900 to 10,300 episodes).
In 2020–21, over 9 in 10 treatment episodes provided to clients were for their own AOD use (92% or around 224,000 episodes) (Table OV.1). Among these episodes:
- The most common principal drugs of concern were alcohol (37% of treatment episodes), amphetamines (24%), cannabis (19%) and heroin (4.6%) (Table Drg.1).
- Clients reported at least 1 additional drug of concern in almost one-third of treatment episodes (31%).
- The number of additional drugs reported was most commonly 1 (19% of episodes) or 2 drugs (7.5%).
- Cannabis (12% of episodes), nicotine (10%) and alcohol (8.2%) were the most common additional drugs of concern (tables Drg.1, Drg.2, Drg.3).
- For the 4 most common principal drugs of concern, the most common treatment setting was non-residential treatment facilities (ranging from 64% to 71%) (tables Drg.19, Drg.27, Drg.35 and Drg.51).
In the 10 years to 2020–21, the total number of treatment episodes for clients’ own drug use increased from 147,000 to 224,000 episodes (Table OV.1). Among these episodes across the period:
- Alcohol remained the most common principal drug of concern each year, and treatment episodes increased by 24% over this period (from 67,400 to 83,600 episodes). However, proportionally, treatment episodes for alcohol in relation to all other drugs of concern fell from 46% to 37%.
- Treatment episodes for amphetamines as a principal drug of concern increased by more than 3 times since 2011–12 (16,900 to 54,300 episodes), although this has declined since 2019–20.
- Around 4 in 5 (79%) episodes for amphetamines were for methamphetamine as the principal drug of concern, increasing from 16% since 2011–12 (from 2,800 to 42,700 episodes).
- Treatment episodes for heroin as the principal drug of concern fell from 8.8% to 4.6% (or 12,900 to 10,300 episodes).
- Treatment episodes for cannabis fluctuated, peaking at 45,000 episodes in 2015–16. In relation to all other drugs of concern, cannabis treatment episodes were most prominent in 2014–15 when they constituted 24% of all episodes (Table Drg.5).
Fluctuations in certain principal drug treatment episodes in particular years may be due to administrative anomalies in the data. For example, the drop in all treatment episodes in the 2014–15 and 2016–17 collection years may be partly related to system changes resulting in under-reporting or partial reporting of the number of episodes in some jurisdictions (See the Data quality statement for further details).

Note: Totals might not add to 100% due to rounding.
Source: AIHW Alcohol and Other Drug Treatment Services National Minimum Dataset Tables Drg1, Drg.2 and Drg.3.
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