Assessing the Efficacy of Medical Cannabis as a Substitution Therapy for Opioids in Chronic Pain Management in South Africa

Background: The global opioid epidemic has intensified, with a 41% increase in use reported in 2020. Medical cannabis has emerged as a potential adjunct in chronic pain management, with evidence suggesting it may reduce opioid dependence and improve patient outcomes. Objectives: To evaluate the efficacy of medical cannabis in reducing opioid consumption, alleviating pain, and improving quality of life among chronic pain patients in South Africa. Methods: A six-month mixed-methods study was conducted across six sites, enrolling 302 participants (53.3% female, 69.2% White). Medical cannabis was prescribed and outcomes assessed via patient questionnaires and verified pharmacy dispensing records. Repeated-measures analysis, regression, and ANOVA were applied to evaluate temporal changes and treatment effects. Results: At baseline, 99.7% reported opioid use. By six months, 72% achieved ≥50% reduction, with a mean reduction of 93% (SD = 17%); 81.8% achieved complete cessation. Repeated-measures analysis confirmed a linear decline in opioid use over time (Wilk’s λ = 0.047, p < 0.001), with significant reductions at each interval (all p < 0.001). Pain severity scores declined from 3.4 to 3.0, with 64% reporting clinically meaningful relief. Treatment type significantly influenced outcomes (F = 3.87, p = 0.022), with a treatment-by-time interaction (p < 0.001) indicating greater improvements among flower and combination users compared to oil alone. Quality-of-life outcomes also improved, with 83.2% reporting better sleep (p = 0.008) and 78.5% reporting improved physical function (p = 0.012). Conclusions: Medical cannabis use was associated with substantial opioid tapering (p < 0.001), clinically meaningful pain reduction (p = 0.022; interaction p < 0.001), and improvements in sleep and physical function. Flower- and combination-based therapies yielded the greatest benefits. Limitations include the non-randomized, observational design and reliance on self-report measures, which may limit causal inference. Nonetheless, findings support medical cannabis as a promising adjunct in chronic pain treatment, meriting further randomized controlled trials.