Cannabis Exposure and Medication Safety in Older Adults: A Comprehensive Review

Abstract

With the increasing legalization and accessibility of cannabis, there has been a notable rise in its use among older adults. This demographic, often characterized by polypharmacy and heightened vulnerability to adverse drug events, faces unique and underexplored risks related to cannabis exposure. This review synthesizes current evidence on the epidemiology, pharmacological mechanisms, risk factors, clinical features, diagnosis, management, and safety considerations associated with cannabis use in older adults, emphasizing the importance of guideline-driven care and interprofessional collaboration to mitigate medication-related harms.

Introduction

The landscape of cannabis use is rapidly evolving, particularly among older adults. Cannabis is increasingly perceived as a therapeutic option for chronic pain, insomnia, and other age-related conditions. However, this population is also at heightened risk for medication interactions and adverse events due to age-related physiological changes and the common use of multiple medications. Understanding the implications of cannabis exposure in this cohort is critical for healthcare providers, as is recognizing the complex interplay between cannabis pharmacodynamics and other commonly prescribed agents.

Epidemiology / Disease Burden

Recent epidemiological data indicate a sharp rise in cannabis use among adults over 65 in North America and Europe. According to surveys published between 2019 and 2023, cannabis use in this group has increased by more than 180% over the past decade. The burden of cannabis-related emergency department visits and hospitalizations has concurrently escalated, often related to neuropsychiatric symptoms, falls, and cardiovascular events. Polypharmacy, prevalent in up to 75% of older adults, further compounds the risk of drug-drug interactions and adverse outcomes.

Pathophysiology

Cannabis exerts its effects primarily via the endocannabinoid system, binding to CB1 and CB2 receptors in the central and peripheral nervous systems. In older adults, age-related changes in receptor density, blood-brain barrier permeability, and hepatic and renal metabolism alter both the pharmacokinetics and pharmacodynamics of cannabinoids. These changes lead to increased bioavailability and half-life, amplifying the risk of toxicity and interaction with other medications metabolized by cytochrome P450 enzymes, such as warfarin, benzodiazepines, and certain antiepileptics.

Risk Factors

Key risk factors for adverse events with cannabis exposure in older adults include polypharmacy, cognitive impairment, frailty, existing cardiovascular or psychiatric comorbidities, and impaired hepatic or renal function. The concurrent use of CNS depressants or anticholinergic medications significantly increases the risk of sedation, delirium, and falls. Genetic polymorphisms affecting CYP450 isoenzymes may further predispose individuals to unpredictable drug responses and heightened toxicity.

Clinical Features

Clinical manifestations of cannabis-related adverse events in older adults are diverse. Acute presentations include confusion, dizziness, orthostatic hypotension, tachycardia, and ataxia. Chronic exposure may exacerbate cognitive decline, precipitate mood disorders, and increase the risk of falls and fractures. Rare but severe complications such as cannabinoid hyperemesis syndrome and cannabis-induced psychosis have also been documented. Differentiating these features from underlying geriatric syndromes is often challenging in clinical practice.

Diagnosis

Diagnosis of cannabis-related adverse effects relies on a thorough history, including detailed questioning about cannabis use (formulations, route, frequency, and dose), concomitant medication review, and assessment of recent changes in cognitive or physical function. Laboratory evaluation is generally non-specific, though toxicology screening may assist in confirming recent exposure. Comprehensive medication reconciliation is critical to identify potential drug interactions and rule out alternative etiologies for presenting symptoms.

Treatment & Management

Management of cannabis-related adverse events begins with cessation of cannabis and supportive care. For mild toxicity, observation and symptomatic management (hydration, fall precautions, reassurance) are often sufficient. Severe neuropsychiatric or cardiovascular symptoms may necessitate hospitalization and multidisciplinary management. Medication review and deprescribing of interacting agents should be considered. Education regarding the risks of cannabis and safer alternatives for symptom management is key, particularly in those with cognitive impairment or high fall risk.

Recent Advances / Emerging Therapies

Recent research has explored the potential for cannabinoids as adjunctive therapy in chronic pain, cancer-related symptoms, and neurodegenerative disorders. However, randomized controlled trials in older adults remain limited, and the safety profile is not well established. Novel formulations such as low-dose or non-psychoactive cannabinoids (e.g., cannabidiol) are under investigation, with early evidence suggesting a more favorable risk-benefit balance. Pharmacogenomic approaches may eventually allow for more personalized risk stratification and dosing.

Guideline Recommendations

Current international guidelines, including those from the American Geriatrics Society and Canadian Geriatrics Society, advise extreme caution with cannabis use in older adults. Recommendations include starting at the lowest possible dose, slow titration, careful monitoring for adverse events, and routine medication reconciliation. Cannabis should be avoided in those with significant cognitive impairment, psychiatric illness, or cardiovascular disease. Shared decision-making and patient education are emphasized as central components of safe prescribing practice.

Conclusion

While cannabis may offer symptomatic relief for certain conditions in older adults, its use is fraught with significant safety concerns due to polypharmacy, age-related physiological changes, and increased susceptibility to adverse drug events. Clinicians must maintain vigilance for potential drug interactions and adverse effects, employ guideline-based risk mitigation strategies, and engage in ongoing patient education. Further research is needed to better define the therapeutic window and safety parameters for cannabis use in this vulnerable population.