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Published: 07 February 2025

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Recent research has fundamentally challenged our understanding of cannabis’s long-term cognitive effects, with emerging evidence suggesting far more complex and persistent impacts than previously understood. A groundbreaking 2025 study from the University of Colorado School of Medicine, coupled with decades-long longitudinal research from New Zealand, has revealed patterns of memory impairment that persist long after cessation of use, raising serious questions about the drug’s long-term safety profile.

The Evolution of Cannabis Use and Potency

• THC potency has more than doubled since the 1970s
• Daily users now number in millions (US)
• UK has seen exponential growth in cannabis seizures

The latter half of the twentieth century witnessed an unprecedented surge in cannabis availability and consumption across the Western world. What began as a countercultural phenomenon has evolved into a mainstream recreational substance, with scientific understanding struggling to keep pace with rapidly changing usage patterns and increasing potency.

The transformation of cannabis potency represents one of the most significant shifts in the drug’s history. Analysis of seizure data reveals that the average THC concentration has more than doubled from 1.50% in 1977 to 3.65% by 1987. Modern high-potency varieties, particularly seedless Sinsemilla, now regularly exceed 7% THC concentration. This escalation in potency coincides with dramatic increases in consumption patterns. Current estimates indicate over 29 million users in the United States alone, with more than 7 million consuming cannabis daily.

The United Kingdom presents a parallel trend, with market research indicating 12% of males and 9% of females aged 15-25 reporting cannabis use. More telling is the seven-fold increase in cannabis seizures to 45,000 kg between 1978-1988, suggesting a substantial expansion of the market. These figures likely underestimate current usage, given the increasing legalisation and normalisation of cannabis consumption.

The Cognitive Impact: Beyond Simple Memory Loss

• Heavy users (>1000 lifetime uses) show 5.5 point IQ decline
• Impact exceeds both tobacco and alcohol’s cognitive effects
• 27% of users fall into moderate-to-heavy use categories

The University of Colorado’s comprehensive study of 1,003 young adults aged 22-36 has revealed patterns of cognitive impairment that extend far beyond traditional concerns about short-term memory loss. The research identified distinct user categories, with 9% classified as heavy users (more than 1,000 lifetime uses), 18% as moderate users (10-999 times), and 73% as nonusers or minimal users (fewer than 10 times).

The Dunedin, New Zealand Longitudinal Study provides even more compelling evidence through its tracking of individuals from birth to age 45. This research reveals that heavy cannabis users experienced an average IQ decline of 5.5 points from childhood to midlife, a finding made more significant when contrasted with nonusers who showed a slight increase of 0.7 points. For context, this decline exceeds that observed in long-term tobacco users (1.5 points) and long-term alcohol users (0.5 points), challenging the common assertion that cannabis poses fewer cognitive risks than legal substances.

Neurobiological Mechanisms and Structural Changes: Recent neuroimaging studies have identified specific structural alterations in the brains of long-term cannabis users, particularly in the hippocampus, a region crucial for memory formation and cognitive processing. The research reveals reduced grey matter volume in multiple hippocampal subregions, including the CA1 region, molecular layer, and dentate gyrus. These changes appear most pronounced when comparing heavy users to both never-users and recreational users.

The significance of these structural changes extends beyond mere volume reduction. The hippocampus contains a high density of cannabinoid receptors, making it particularly susceptible to long-term cannabis exposure. Research suggests these structural alterations may represent a neurobiological mechanism underlying the observed cognitive deficits, though the relationship appears more complex than initially theorised.

Working Memory and Daily Function

• Deficits persist after 6 weeks of monitored abstinence
• Impacts range from basic conversation to complex problem-solving
• Effects most pronounced during critical developmental periods

Working memory, often described as the brain’s notepad, proves particularly vulnerable to cannabis’s effects. This system, essential for temporarily holding and manipulating information, shows significant impairment in heavy users. The impact extends beyond laboratory tests to real-world functions, affecting activities ranging from following conversations to complex problem-solving.

Research indicates that these working memory deficits persist even after extended periods of abstinence. A controlled study following cannabis-dependent adolescents through six weeks of monitored abstinence found that while some improvement occurred, significant deficits remained compared to control groups. This persistence suggests that heavy cannabis use during critical developmental periods may lead to lasting alterations in cognitive processing systems.

Processing Speed and Learning Capacity: Beyond memory effects, cannabis appears to significantly impact processing speed and learning capacity. The University of Colorado study identified reduced brain activity during cognitive tasks, particularly in regions responsible for information processing and decision-making. This reduction in processing speed manifests in slower reaction times, decreased ability to quickly assimilate new information, and difficulties in maintaining attention during complex tasks.

The learning implications prove particularly concerning. Heavy users demonstrate reduced capacity for acquiring and retaining new information, a deficit that persists even after controlling for baseline cognitive ability and educational background. This impairment in learning capacity raises serious questions about the impact of cannabis use on educational and professional development, particularly for young users.

The Abstinence Paradox: One of the most troubling findings emerging from recent research concerns the persistence of cognitive deficits after cessation of cannabis use. The common assumption that cognitive function fully recovers after stopping cannabis use appears increasingly questionable. Studies of former heavy users (“quitters”) reveal ongoing cognitive deficits, particularly in memory and processing speed, even after extended periods of abstinence.

The Schwarz study, focusing on cannabis-dependent adolescents, found that while some cognitive improvement occurred during six weeks of monitored abstinence, significant deficits remained compared to control groups. This persistence of cognitive impairment suggests that heavy cannabis use may lead to lasting alterations in brain function, particularly when use occurs during critical developmental periods.

Vulnerability Factors and Risk Assessment

• Use before age 18 correlates with severe cognitive deficits
• Regular use threshold: 4+ days per week
• Lifetime exposure over 1,000 uses indicates significant risk

Research has identified several key factors that appear to increase vulnerability to cannabis-related cognitive impairment. Early onset of use, particularly before age 18, correlates with more severe and persistent cognitive deficits. Regular use, defined as four or more days per week, appears to cross a threshold for increased risk of permanent impairment. The consumption of high-potency products and cumulative lifetime exposure exceeding 1,000 uses also emerge as significant risk factors.

Individual differences in vulnerability remain poorly understood. Genetic factors, pre-existing cognitive function, and concurrent substance use may all modulate the impact of cannabis on cognitive function. This variability in individual response complicates risk assessment and suggests the need for personalised approaches to prevention and intervention.

Clinical Implications and Treatment Considerations: The emerging understanding of cannabis’s cognitive effects has significant implications for clinical practice. The persistence of cognitive deficits after cessation suggests the need for comprehensive cognitive assessment in treatment planning. Clinicians must consider the potential impact of these deficits on treatment engagement and success, particularly in cognitive-behavioural interventions requiring intact executive function.

The relationship between cannabis-related cognitive impairment and mental health outcomes requires particular attention. Research suggests that cognitive deficits may compound existing mental health issues and potentially increase vulnerability to conditions such as anxiety and depression. This interaction between cognitive impairment and mental health emphasises the need for integrated treatment approaches.

Public Health and Policy Implications: The accumulating evidence of persistent cognitive effects challenges current public health messaging around cannabis use. The common perception of cannabis as a relatively harmless substance requires serious reconsideration, particularly regarding long-term cognitive risks. Public health initiatives must balance acknowledging the legitimate medical applications of cannabis while accurately conveying the risks of regular recreational use.

The increasing potency of available cannabis products adds urgency to this public health challenge. The dramatic increase in THC concentration over recent decades suggests that historical studies may underestimate the cognitive risks posed by contemporary cannabis products. This evolution in product potency necessitates updated research and revised risk assessments.

Future Research Directions: Several critical questions remain unanswered and require further investigation. The relationship between cannabis use and early-onset dementia represents a particularly urgent area for research, given the aging population of long-term cannabis users. The potential for cognitive recovery after cessation, particularly in heavy users, requires longer-term follow-up studies.

The interaction between cannabis use and other risk factors for cognitive decline, including genetics, lifestyle factors, and concurrent substance use, needs more detailed examination. Additionally, the impact of different cannabis consumption methods and varying THC/CBD ratios on cognitive outcomes requires systematic investigation.

Closing Considerations: The science is clear: heavy cannabis use rewires memory function, and not for the better. Decades of research have demolished the myth of cannabis as a consequence-free substance. The brain pays a price for sustained exposure, particularly in memory and cognitive processing. Regular users can’t simply quit and reset – the damage often persists.

We must confront an uncomfortable truth: increasing potency and widespread availability have created a cognitive time bomb. Recreational users might dodge the bullet, but heavy users face a stark reality of potentially permanent mental fog. Public policy lags dangerously behind the evidence. We need better education, smarter intervention strategies, and honest conversations about the real costs of long-term use.

The next decade will prove critical. We’re watching an unprecedented experiment unfold as millions embrace a substance whose long-term effects we’re only beginning to grasp. Ignore the mounting evidence of cannabis’s cognitive toll, and we risk creating a generation that literally cannot remember why they should have paid attention. (Source: WRD News)

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Published: 06 February 2025

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Medicine that’s Smoked? Who is ‘Prescribing’ this Toxin?

The growing acceptance of medicinal cannabis has led to increased prescription rates worldwide, with smoking remaining the predominant administration method despite mounting scientific evidence questioning its safety and efficacy. Recent research has revealed significant concerns about particulate matter emissions, inconsistent drug delivery, and potential long-term health consequences that challenge the therapeutic validity of this administration route. This analysis examines the current scientific evidence regarding smoked medicinal cannabis, highlighting critical concerns that healthcare providers and patients should consider.

Particulate Matter Emissions: A Major Health Risk

Recent comparative studies between cannabis and tobacco cigarettes have revealed alarming data about particulate matter (PM) emissions. Laboratory analysis demonstrates that cannabis smoke contains substantially higher PM levels in second-hand smoke than tobacco cigarettes, with PM1 emissions exceeding reference cigarettes by 105%. Cannabis mixed cigarettes similarly showed elevated emissions, with PM10 levels 93% higher than reference cigarettes. These findings are particularly concerning given that the largest proportion of particle mass consists of particles with diameters less than 1μm.

The implications of these elevated PM levels extend beyond the immediate user. Second-hand cannabis smoke presents a significant environmental health hazard, with PM concentrations often exceeding safety thresholds established for indoor air quality. The higher PM emissions from cannabis suggest that even in well-ventilated spaces, bystanders may be exposed to potentially harmful levels of particulate matter.

Research indicates that these fine particles can penetrate deep into lung tissue, potentially causing both acute and chronic respiratory issues. The smaller particle size distribution in cannabis smoke compared to tobacco smoke suggests these particles may reach deeper into the respiratory system, potentially causing more significant damage to alveolar tissue.

Pharmacokinetic Complexities and Delivery Inconsistencies

Detailed pharmacokinetic studies reveal fundamental problems with smoking as a delivery method for medicinal compounds. THC delivery yields through smoking are remarkably inefficient, with studies showing yields ranging from just 7.2% to 28.0%. This inefficiency stems from multiple factors: up to 50% of cannabinoids are lost in side-stream smoke, 30% are destroyed by pyrolysis, and approximately 10% remain trapped in the cigarette butt.

The pharmacokinetic profile of smoked cannabis follows a complex three-compartment model, leading to highly variable absorption rates and unpredictable blood concentration levels. This variability makes it extremely difficult for healthcare providers to establish reliable dosing protocols or predict therapeutic outcomes.

Temperature-Dependent Composition Changes

Recent research has uncovered significant changes in cannabis cigarette composition during the smoking process. As smoking progresses, a temperature gradient develops along the cigarette, ranging from 470°C to 812°C at the burning tip to under 100°C at the mouth end. This gradient creates a complex series of chemical transformations that fundamentally alter the therapeutic profile of the medicine. Laboratory analysis demonstrates that the neighbouring section to the burning tip maintains temperatures above 300°C, while the following section ranges between 100°C and 300°C, creating distinct zones of chemical activity.

The temperature variation leads to complex fluid dynamics within the cigarette structure. As hot air is drawn through the glowing end during inhalation, it creates thermal convection currents that affect compound distribution. Research shows that air temperature during inhalation typically exceeds the temperature of the fixed cannabis matter, leading to additional compound mobilisation and potential degradation. These thermal dynamics significantly impact the consistency of drug delivery and create unpredictable concentration gradients throughout the cigarette.

Decarboxylation and Compound Migration

The high temperatures near the burning tip cause rapid decarboxylation of cannabinoids, converting THCA to THC. However, this process is not uniform throughout the cigarette. Analysis shows that sections closer to the mouth end contain higher concentrations of active compounds, as these molecules evaporate from the hot zones and recondense in cooler regions. Research demonstrates that after smoking just one quarter of a cigarette, the fraction of decarboxylated THC increases from 0.05 to 0.47 in sections closest to the burning end.

The movement of compounds away from high-temperature zones is critical for preserving therapeutic molecules that would otherwise be destroyed. Studies indicate that without this migration, most cannabinoids would be fully oxidised to CO2 and water in the highest temperature zones. However, the migration process itself introduces new variables affecting drug delivery. Cannabinoid vapours can exceed saturation in cooler regions, leading to condensation and the formation of small droplets. Some droplets reach the inhaled smoke, while others become trapped in the cigarette matrix, creating inconsistent delivery patterns.

Differential Vaporisation Effects

The varying boiling points of different compounds lead to a sequential release pattern during smoking. Monoterpenes, with their lower boiling points, reach the smoke first, followed by sesquiterpenes and cannabinoids. This staged release means early puffs contain primarily monoterpenes, while later puffs deliver higher concentrations of cannabinoids. Research shows that THC and CBD, with boiling points around 425°C, have partial vapor pressures of approximately 6.7 and 40 Pa at 155°C and 190°C respectively, affecting their release patterns.

The temperature gradient also influences the spatial distribution of compounds within the cigarette. Studies reveal that monoterpenes, due to their higher volatility, can move further from the hot zone and often concentrate in the bottom section of the cigarette. In contrast, sesquiterpenes and cannabinoids tend to recondense in closer proximity to their evaporation point. This differential movement creates zones of varying therapeutic compound ratios throughout the cigarette, making each puff potentially different in composition from the last.

Clinical Efficacy and Therapeutic Limitations

The inconsistent nature of smoked cannabis delivery has significant implications for clinical efficacy. Studies of pain management outcomes show highly variable results, partly due to the unpredictable nature of compound delivery through smoking. Research indicates that if one half of a cigarette is used in the morning and the other half at night, the evening dose might contain nearly twice the concentration of active compounds compared to the morning dose. This variability makes it extremely difficult for healthcare providers to establish reliable dosing protocols.

These delivery inconsistencies particularly impact patients using cannabis for chronic conditions requiring precise dosing. Clinical studies demonstrate that the variable ratio of cannabinoids to terpenes throughout the smoking session can affect the entourage effect, potentially altering therapeutic outcomes. Furthermore, research shows that terpenes, which may contribute to the analgesic effects of cannabis, are often inhaled before cannabinoids due to their lower boiling points, potentially reducing the synergistic benefits of these compounds.

The timing and sequence of compound delivery also affect therapeutic outcomes. Studies indicate that monoterpenes, which may have anxiolytic and anti-inflammatory properties, are largely delivered in the early stages of smoking. This means that patients seeking specific therapeutic effects might receive inconsistent benefits depending on how much of the cigarette they consume and in what timeframe. Additionally, research shows that delivery yields vary significantly based on smoking parameters, with factors such as puff frequency, puff length, and puff volume all affecting the concentration and ratio of therapeutic compounds in the inhaled smoke.

Cost-Effectiveness Considerations

While some analyses suggest potential cost-effectiveness for specific conditions like neuropathic pain, these studies often fail to account for several critical factors. The high wastage rate of active compounds during smoking significantly impacts the economic efficiency of this delivery method. Additionally, the potential long-term healthcare costs associated with respiratory issues from chronic smoke exposure are rarely factored into these analyses.

A comprehensive cost analysis reveals that when accounting for product wastage, healthcare costs, and variable absorption rates, smoking may be less economically viable than alternative delivery methods. The need for larger quantities of cannabis to achieve therapeutic effects due to poor bioavailability further impacts cost-effectiveness.

Long-Term Health Implications

The chronic effects of medicinal cannabis smoking present complex health concerns that extend beyond immediate therapeutic benefits. Research demonstrates that regular exposure to cannabis smoke results in significant changes to respiratory tissue structure and function. Laboratory studies have identified that cannabis smoke causes distinctive damage patterns to small blood vessels in lung tissue, with observed scarring patterns different from those seen in tobacco smoke exposure. This vascular damage may have cumulative effects over time, potentially leading to reduced gas exchange efficiency and compromised respiratory function.

Particulate matter exposure from cannabis smoke shows unique characteristics that may pose specific health risks. Studies reveal that cannabis smoke particles have different size distributions and chemical compositions compared to tobacco smoke, with a higher proportion of particles in the sub-micron range. These smaller particles can penetrate deeper into lung tissue and may have greater potential for systemic distribution throughout the body. Research indicates that particles smaller than 1μm can cross the blood-brain barrier and potentially impact neurological function over time.

The cardiovascular implications of long-term cannabis smoke exposure are particularly concerning. Studies have documented changes in blood vessel function and inflammatory markers in regular cannabis smokers, even in the absence of tobacco use. Research shows that cannabis smoke exposure can lead to increased blood pressure variability and altered heart rate patterns, potentially contributing to long-term cardiovascular risk. These effects appear to be independent of the therapeutic benefits of cannabinoids and may represent a distinct risk factor for cardiovascular disease.

Emerging research suggests potential immune system effects from chronic cannabis smoke exposure. Laboratory studies have identified alterations in immune cell function and inflammatory response patterns in regular cannabis smokers. These changes may have implications for susceptibility to respiratory infections and other immune-mediated conditions. Studies indicate that regular cannabis smoking can modify the expression of immune system genes, potentially affecting long-term immune function.

The potential for dependency and tolerance development presents another long-term concern. Research utilising intracranial self-stimulation (ICSS) models demonstrates that chronic cannabis smoke exposure can lead to significant changes in reward system function. Studies show that after continuous exposure, administration of CB1 receptor antagonists induces dose-dependent increases in ICSS thresholds, suggesting the development of physical dependence. This adaptation may affect both therapeutic efficacy and the potential need for dose escalation over time.

Epigenetic changes associated with long-term cannabis smoke exposure represent a newly recognised area of concern. Research indicates that regular exposure to cannabis smoke can alter DNA methylation patterns and histone modifications in respiratory tissue. These changes may persist even after cessation of smoking and could potentially influence disease susceptibility and therapeutic response patterns. Studies suggest that these epigenetic modifications may affect not only respiratory function but also systemic inflammation and immune response patterns.

The interaction between chronic cannabis smoke exposure and aging presents additional complexities. Research indicates that older individuals may be more susceptible to the negative effects of particulate matter exposure and may experience different patterns of cardiovascular and respiratory complications. Studies show that the combination of age-related changes in lung function and cannabis smoke exposure may accelerate certain aspects of respiratory aging, potentially leading to earlier onset of age-related respiratory conditions.

Respiratory System Impact

The high temperature of cannabis smoke and its particulate composition can cause direct damage to respiratory tissue. Studies indicate that cannabis smoke exposure leads to:

• Inflammation and damage to small blood vessels in lung tissue
• Potential scarring and reduced gas exchange efficiency
• Increased susceptibility to respiratory infections

These findings are particularly relevant given that many medical cannabis users consume the drug daily for extended periods. The cumulative effect of chronic exposure to high-temperature smoke and elevated PM levels may lead to progressive respiratory dysfunction.

Cannabis smoke contains many of the same carcinogenic compounds found in tobacco smoke, but often in higher concentrations. While definitive longitudinal studies are lacking, the biological plausibility for increased cancer risk cannot be ignored, especially given the high temperature of cannabis combustion and increased tar exposure per inhalation.

Safety Protocols and Quality Control

The lack of standardised safety protocols for medicinal cannabis smoking presents critical concerns that extend beyond basic quality control issues. Research reveals significant variations in product composition, with THC content varying from 14.3% to 23.5% even in controlled studies. This variability is compounded by differences in cigarette construction, with studies showing that factors such as filter design dramatically impact compound delivery. For instance, analysis of commercial products found that star-shaped cutouts in filters, intended to improve airflow, actually decrease filtration efficiency and lead to increased particulate matter exposure.

The physical characteristics of cannabis cigarettes significantly influence mainstream smoke composition and therapeutic delivery. Laboratory studies demonstrate that paper type, paper porosity, and filter composition can alter cannabinoid delivery by up to 40%. Research indicates that recycled, less robust wrapping materials may influence carbonyl quantities in smoke, while differences in filters impact the reduction of harmful volatile constituents. Fast-burning, bleached, and flavoured papers have been shown to contribute to higher levels of aerosol toxicants, with formaldehyde levels particularly elevated in products using certain paper types.

Quality control challenges extend to the cultivation and processing of medical cannabis. Studies show that terpenoid content can vary by up to 40-fold across different cannabis varieties, even when grown under standardised conditions. This variation significantly impacts both therapeutic efficacy and potential health risks, as different terpenoid profiles alter the formation of harmful compounds during combustion. Additionally, research indicates that storage conditions and product age can significantly affect cannabinoid degradation rates and the formation of potentially harmful compounds like cannabinol (CBN).

Future Directions and Research Needs

Current research gaps in smoked medicinal cannabis are substantial and multifaceted. Longitudinal studies examining carcinogenic potential and other health hazards are notably absent, with most existing data derived from recreational use patterns. Studies indicate that while there isn’t conclusive evidence linking cannabis smoking to cancer, biological plausibility exists for multiple adverse health outcomes, including testicular germ cell cancer and cardiovascular complications.

Pharmacokinetic research reveals critical areas requiring investigation. Studies using three-compartment pharmacokinetic models show complex distribution patterns that aren’t fully understood. Current data indicates that chronic cannabis smoke exposure has rewarding properties that may complicate therapeutic use, with studies showing significant changes in intracranial self-stimulation thresholds after repeated exposure. This suggests a need for research into dependency potential and its impact on therapeutic applications.

Alternative Delivery Systems

Recent research into alternative delivery methods has yielded promising results that warrant further investigation. Electronic drug-delivery systems (EDDS) and whole plant vaporisers have demonstrated lower toxicant yields compared to combusted material. Studies show that vaporised pure CBD produces significantly greater subjective drug effects and pleasant drug effects compared to oral administration, while causing less respiratory irritation than smoking.

The development of temperature-controlled vaporisation systems shows particular promise. Research indicates that precise temperature control can selectively vaporise desired compounds while minimising the formation of harmful byproducts. Studies demonstrate that vaporisation between 160-180°C effectively releases cannabinoids while producing significantly fewer polyaromatic hydrocarbons compared to smoking. However, challenges remain in standardising these devices and ensuring consistent delivery across different cannabis preparations.

Standardisation Protocols

The development of comprehensive quality control standards requires addressing multiple technical challenges. Research indicates that conventional cigarette manufacturing is highly automated with established quality metrics, but cannabis products lack similar standardisation. Studies show that quality control measures must account for complex interactions between product characteristics and delivery efficiency.

Analytical methods for assessing product quality need refinement. Current research employs various techniques including high-performance liquid chromatography (HPLC) and gas chromatography (GC) analysis, but standardised protocols for measuring critical parameters are lacking. Studies demonstrate that methods must be validated for at least 12 cannabinoids and 25 terpenes to adequately characterise product composition. Additionally, research indicates that current methods for measuring delivery efficiency, which show variations from 7.2% to 28.0%, need standardisation to ensure consistent therapeutic delivery.

Recommendations

The scientific evidence strongly suggests that smoking medical cannabis, despite its widespread use, presents significant health risks and therapeutic limitations that outweigh its potential benefits for most medical applications. The combination of high particulate matter emissions, poor delivery efficiency, inconsistent drug absorption, and potential long-term health consequences makes it a problematic choice for medical treatment.

Healthcare providers should prioritise alternative delivery methods when prescribing medicinal cannabis, particularly for chronic conditions requiring long-term use. Patient education about the risks associated with smoking should be mandatory, and development of standardised, safer administration methods should be prioritised by the medical and research communities.

The continued use of smoking as a primary delivery method for medicinal cannabis appears to be driven more by historical and cultural factors than by scientific evidence of safety or efficacy. As our understanding of cannabis pharmacology advances, the development of safer, more reliable administration methods becomes increasingly important for realising the full therapeutic potential of cannabis-based medicines. (Source: WRD News)

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Published: 04 February 2025

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One potential harm of increased access to cannabis is poisoning. It is widely believed that cannabis is safe in overdose,^{3 but it can cause central nervous system (CNS) excitation, CNS depression, hallucinations, psychosis, and cardiac dysrhythmias.4 The risk of severe toxicity is greater for children, in whom it can lead to apnoea and coma; in one United States study, 32 of 60 children (0–10 years) hospitalised with cannabis intoxication required intensive care.5 Several studies have reported increases in the number of poisonings following medicinal and recreational cannabis legalisation, particularly in children.6 Edibles are particularly high risk products because of their palatability and the possibility of large ingestions.2 Most reports on this problem are from North America.6}

In Australia, the medicinal use of cannabidiol (CBD) was legalised in June 2015, and that of cannabis and tetrahydrocannabinol (THC) in November 2016.^{7 We therefore evaluated recent cannabis poisoning exposures in Australia, stratified by ingestion intent, age group, and product type. We analysed data from the New South Wales Poisons Information Centre (NSWPIC), which receives about 50% of all calls to Australian poisons information centres; 65% of calls are from within NSW, 35% from other states.8 We extracted data on demographic and exposure characteristics, patient disposition, and cannabinoid product types for calls during 1 July 2014 – 30 June 2024. We calculated crude and age-adjusted population exposure call rates (Supporting Information, supplementary methods), and used Joinpoint regression (version 4.9.0.1) to estimate annual percentage changes (APCs) in age-adjusted rates and to detect trend change points. The study was approved by the Sydney Children's Hospitals Network Human Research Ethics Committee (2021/ETH00165).}

There were 3796 calls about cannabis poisoning exposures (2039 regarding exposures of boys or men, 54%) during 2014–24. The exposed person exhibited symptoms of poisoning at the time of the call in 3184 cases (84% of calls); 2783 people (74%) were in hospital at the time of the call or were referred to hospital (Supporting Information, table 1). The number of calls increased during 2014–24 by 12.8% per year (95% confidence interval [CI], 10.3–15.4% per year), and no trend change points were detected (Box 1). Intentional cannabis exposures were reported by 2981 calls (79% of calls), and the number increased by 9.2% (95% CI, 6.3–12.2%) per year. Unintentional cannabis exposures were re

The age-adjusted cannabis poisoning exposure rate was highest for adolescents (15–19 years; 11.4 calls per 100 000 population per year); the age-adjusted rate for unintentional exposures was highest for toddlers (1–4 years; 1.9 calls per 100 000 population per year) (Supporting Information, table 2).

We found that the number of cannabis poisonings reported increased significantly in Australia during 2014–24, particularly exposures of children and adolescents. The reported number of exposures to edibles, which pose a particular risk for young children,^{13 has increased. Our findings are relevant to discussions of increasing access to medicinal cannabis and legalising its recreational use. Lessons learned overseas with different legislative models could be applied in Australia. For example, the sale of edibles is not permitted in some Canadian provinces, and significantly more children are hospitalised with cannabis intoxication in provinces where they are sold.2 While using orally ingested cannabis forms may be less harmful in the long term than smoking cannabis, the acute poisoning risk posed by edible forms of cannabis must be considered. Particular caution needs to be applied to confectionery forms that are attractive for children.}

(For complete research - Source: The Medical Journal of Australia 2025)

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Published: 28 January 2025

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Cannabis & Driving – Whilst old school sobriety tests will confirm intoxication in most instances, the 'lollipop – lick sticks’ ensures the so called 'seasoned' users and those who call their intoxicating substance ‘medicinal’ are also taken off the road. No one should drive any vehicle intoxicated - ever.

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1. Rising Need for Roadside Drug Testing
2. Cannabis and Driving: Victorian Law Change for ‘Medicinal’ Cannabis Users – But is Road Safety Seriously Compromised?