215: Medicinal Cannabis for Pain Management: Harm Reduction Framework for Patients Using Illicit Cannabis

Topic: Clinical Science
Subtopic: Non-specific to any diagnosis, Pharmacological treatments, Epidemiology, Treatment/management

Background and Aims: Chronic pain is a leading cause of disability worldwide, and many patients self-medicate with cannabis obtained from unregulated black market sources. While this may provide symptomatic relief, black market cannabis (BMC) use carries avoidable risks, including unknown potency, contamination, reliance on combustion, and lack of clinical guidance. Prescribed medicinal cannabis (MC) offers a regulated alternative, enabling safer dosing, quality assurance, and structured clinical support. Patients accessing MC often transition from BMC; however, there is limited Australasian data examining outcomes during this process. This audit aimed to evaluate the impact of clinic-based MC prescribing on patient-reported outcomes, cannabis use patterns, harm reduction behaviours, and changes in concomitant pharmaceutical medication use in patients previously reliant on BMC. Understanding these transitions may help inform best-practice models of care and support harm minimisation strategies in chronic pain management.

Methods: We conducted a retrospective clinical audit of 260 consecutive patients (median age 38 years; 73.8% male) who were regular users of BMC prior to engagement with The Cannabis Clinic in New Zealand. All patients completed at least one follow-up consultation, with data extracted from May 2025. Data were collected by eight clinicians using a standardised template across 20 variables, including demographics, clinical indications, cannabis use patterns (route and frequency), ongoing illicit use, symptom outcomes, concomitant pharmaceutical medications, and adverse events. Chronic pain was a primary indication in 122 patients (46.9%). Routes of administration were categorised as smoking, vaporising, or oral use. Symptom improvement was assessed using patient-reported outcomes at follow-up. Changes in pharmaceutical medications were evaluated for reduction or cessation. Adverse events were recorded. Data were analysed descriptively using frequencies, percentages, means, and medians, with comparisons between baseline and follow-up assessing changes in use patterns and harm reduction behaviours.

Results: Chronic pain was reported in 46.9% of the cohort, frequently co-occurring with insomnia (68.1%) and anxiety (47.3%). At baseline, 77.7% of patients used smoked cannabis. Following clinic engagement, 64.4% transitioned to non-combustion routes, reflecting meaningful harm reduction. Overall, 89.5% ceased black market cannabis use; financial cost was the primary barrier among those who did not.
Symptom improvement was reported by 99.6% of respondents, including those with chronic pain. Mean monthly cannabis consumption decreased by 28.7% (median 34.5%; p < 0.001), suggesting improved dosing efficiency. CBD use increased from 6.2% pre-clinic to 48.8% at follow-up.
Among patients taking pharmaceutical medications, 62.2% reduced or ceased at least one agent, including opioids (n=14), gabapentinoids (n=9), and NSAIDs (n=9). No cases of psychosis or deterioration in mental state were observed. Adverse events were infrequent (1.9%) and mild.

Conclusions: In this cohort, structured prescribing of medicinal cannabis was associated with clinically meaningful benefits for patients with chronic pain, alongside substantial harm reduction. Transitioning from illicit to regulated cannabis use reduced reliance on smoking, supported safer routes of administration, and facilitated exit from the black market. High rates of patient-reported symptom improvement were observed, with reduced overall cannabis consumption suggesting improved dosing efficiency. Importantly, many patients reduced or ceased concomitant analgesic and psychotropic medications, including opioids and gabapentinoids, highlighting the potential role of medicinal cannabis within multimodal pain management. Adverse events were infrequent and mild, with no serious psychiatric complications observed. Financial cost remained a key barrier to sustained transition.
These findings support medically supervised medicinal cannabis as a pragmatic, harm minimisation approach for patients already using cannabis for pain, with potential to improve outcomes while reducing risks associated with unregulated use.

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Presenting Author: Dr. Shehnaz Hussain
Submitting Author: Shehnaz Hussain

Senior Author: Dr. Shehnaz Hussain and Dr. William Parkyn

IASP 2026 Global Year theme of Neuropathic Pain: No

• Dr William Parkyn: MBChB (Otago) FRNZCGP, PG Dip ObsMedGyn (Auckland), PG Cert Emergency Med (ACEM) - The Cannabis Clinic New Zealand