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The National Wastewater Drug Monitoring Program (NWDMP) measures the presence of substances in sewerage treatment plants across Australia. Measurement of cannabis consumption was included for the first time in the August 2018 collection. It is important to note that an average dose was not defined for cannabis because reliable dose figures were not available. As such, cannabis was not included in the comparison of the highest consumed drugs monitored by the program. For further information, see Box HARM2 and Data quality for the National Wastewater Drug Monitoring Program.
Consumption of cannabis increased in many jurisdictions after the initial COVID restrictions were put in place in March 2020. Consumption returned to previous levels before reaching record highs in both capital cities and regional areas in August 2021 (ACIC 2022).
Data from report 18 of the NWDMP indicate that the estimated population-weighted average consumption of cannabis in both capital cities and regional areas increased from April 2022 to August 2022. On average, consumption in regional areas continued to exceed capital cities (ACIC 2023).
For state and territory data, see the National Wastewater Drug Monitoring Program reports.
Box CANNABIS1: What is medicinal cannabis?
Prior to 2016, cannabis was classified as an illegal narcotic under Australian law. This changed in February 2016, when the National Drugs Amendment Act 2016 established a national licensing and permit scheme to enable the cultivation, production, and manufacture of cannabis for medicinal and related research purposes. Under this scheme, specific patient groups can now access medicinal cannabis products under strict medical supervision. Cannabis cultivated for other purposes remains illegal.
Medicinal cannabis typically refers to use of cannabis that is prescribed by a healthcare professional. However, in the 2019 National Drug Strategy Household Survey, this included any use of cannabis for medical purposes, regardless of whether a doctor prescribed it.
In 2019, the NDSHS included 2 new questions regarding medical use of cannabis – if respondents had recently used cannabis for medical purposes, and whether the cannabis was prescribed by a doctor (AIHW 2020).
- Of people aged 14 and over who had used cannabis in the previous 12 months in 2019, 6.8% always used it for medical purposes and 16.3% used it for both medical and non-medical reasons.
- Of those who had recently used cannabis for medical purposes, 1.8% always obtained cannabis with a prescription and 2.1% sometimes did.
- When asked about their usual source, around half (51%) of people who had recently used cannabis medically said they normally obtained it from a friend, and 22% purchased it from a dealer (AIHW 2020).
Compared with people who did not use cannabis for medical purposes, people who had recently used cannabis for medical purposes only were:
- Typically older (43% aged 50 and over) than people who used cannabis non-medically (16%).
- More likely to live in the lowest socioeconomic areas (32% compared with 20%) and Inner regional areas (28% compared with 17.0%).
- More likely to experience chronic pain (53% compared with 6.9%), very high levels of psychological distress (27% compared with 9.7%) and poor or fair health (33% compared with 10.4%).
- Less likely to have recently used another illicit substance (20% compared with 44%) but more likely to smoke tobacco (51% compared with 39%).
- More likely to use cannabis daily or weekly (56% compared with 29%).
- More likely to use cannabis oil (23% compared with 4.5%), and less likely to use leaf (27% compared with 51%) (AIHW 2020).
Poly drug use
Poly drug use is defined as the use of mixing or taking another illicit or licit drug whilst under the influence of another drug. Cannabis use is also highly correlated with the use of tobacco, alcohol and other drugs. This makes measuring the effects of cannabis alone difficult and potentially increases risks for users.
The 2019 NDSHS showed that alcohol was the most common substance used concurrently with cannabis. Of those recent cannabis users who also consumed alcohol, 62% exceeded the single occasion risk guidelines at least monthly and 39% exceeded the lifetime risk guidelines (AIHW 2020, Table 1.3).
The most common other drugs concurrently used by recent cannabis users were:
- Tobacco (29%)
- Cocaine (25%)
- Ecstasy (19.7%)
- The non-medical use of pharmaceuticals (14.1%) (AIHW 2020, Table 1.3).
Data on alcohol and other drug-related ambulance attendances are sourced from the National Ambulance Surveillance System (NASS). Monthly data for 2021 are currently available for New South Wales, Victoria, Queensland, Tasmania and the Australian Capital Territory. It should be noted that some data for Tasmania and the Australian Capital Territory have been suppressed due to low numbers. Please see the data quality statement for further information.
In 2021, the proportion of cannabis-related ambulance attendances where multiple drugs were involved (excluding alcohol) ranged from 42% of attendances in Tasmania to 49% of attendances in Victoria (Table S1.10).
For related content on multiple drug involvement see Impacts: Ambulance attendances.
For related content on cannabis impacts and harms, see also:
The effects of cannabis (like all drugs) vary from one person to another including, but not limited to, the amount consumed, the mode of administration, the user’s previous experience, mood and body weight (NSW Ministry of Health 2017). The active drug in cannabis makes its way into the bloodstream more quickly when cannabis is smoked, compared to when it is orally ingested. Ongoing and regular use of cannabis is associated with a number of negative long-term effects. Regular users of cannabis can become dependent and commonly reported symptoms of withdrawal include anxiety, sleep difficulties, appetite disturbance and depression (Hall & Degenhardt 2009; Nielsen & Gisev 2017).
An overview of some of the short and long-term effects of cannabis are provided in Table CANNABIS1.
Table CANNABIS1: Effects of cannabis
- Mild euphoria, relaxation and reduced inhibitions
- Perceptual alterations, including time distortion and intensification of ordinary experiences
- Feelings of hunger
- Panic reactions, confusion and feelings of paranoia – mainly reported by naïve users
- Nausea, headache and reddened eyes
- Increased heart rate for up to 3 hours after smoking
- Dizziness, with impaired balance and coordination
- Physical dependence
- Upper respiratory tract cancers, chronic bronchitis and permanent damage to the airways when smoked
- Cardiovascular system damage
- Mental health conditions including depression
- Poor adolescent psychosocial development
Source: Adapted from (Hall & Degenhardt 2009; Nielsen & Gisev 2017; NSW Ministry of Health 2017).
Burden of disease and injury
The Australian Burden of Disease Study 2018, found that cannabis use contributed to 0.3% of the total burden of disease and injuries in 2018 and 10.2% of the total burden due to illicit drugs (AIHW 2021b; Table S2.5). Drug use disorders (excluding alcohol) (11%) contributed most to the burden due to cannabis use, followed by poisoning (10%). Only a small proportion (3% or less) of the burden of schizophrenia, anxiety disorders, road traffic injuries and depressive disorders was attributable to cannabis use (AIHW 2021).
Data on alcohol and other drug-related ambulance attendances are sourced from the National Ambulance Surveillance System (NASS). Monthly data are presented in 2021 for people aged 15 years and over for New South Wales, Victoria, Queensland, Tasmania and the Australian Capital Territory.
In 2021, for cannabis-related ambulance attendances in these jurisdictions:
- Rates of attendances ranged from 85.3 per 100,000 population in New South Wales to 134.1 per 100,000 population in Tasmania.
- 3 in 5 (60%) of total attendances were for males.
- Ambulance attendances for cannabis are typically a younger cohort of people, with the highest rates of attendances in people aged 15–24. Rates of attendance ranged from:
- 214.8 per 100,00 population in New South Wales (2,102 attendances), to
- 341.3 per 100,000 population in the Australian Capital Territory (187 attendances) (Table S1.9).
Figure CANNABIS3: Ambulance attendances for cannabis, by age, sex and selected states and territories, 2021