Clinical Takeaway
Many people with endometriosis already use cannabis for symptom relief, but rigorous clinical evidence for its effectiveness has been lacking. This Australian trial attempted to evaluate the safety and feasibility of two medicinal cannabis formats, inhaled vaporized THC flower and an oral oil, compared to placebo in a randomized controlled design. The study focused on whether such a trial could be practically conducted and safely tolerated before drawing conclusions about efficacy.
#20 Challenges in conducting a feasibility randomized controlled trial of medicinal cannabis for endometriosis pain in Australia.
Citation: Chesterman Susan et al.. Challenges in conducting a feasibility randomized controlled trial of medicinal cannabis for endometriosis pain in Australia.. Complementary therapies in clinical practice. 2025. PMID: 41005282.
Design: 5 Journal: 0 N: 0 Recency: 2 Pop: 2 Human: 1 Risk: 0
Endometriosis patients report widespread off-label cannabis use for symptom management despite absent clinical evidence of efficacy, making this feasibility study essential for establishing whether properly controlled trials can definitively evaluate cannabis as a potential analgesic option in this refractory pain population. The study’s assessment of safety, acceptability, and feasibility across multiple cannabis delivery methods provides critical preliminary data needed to design adequately powered randomized controlled trials that could inform evidence-based prescribing guidelines for endometriosis pain management. Given the significant burden of endometriosis-related pain and current limitations of conventional pharmacotherapy, demonstration of cannabis efficacy through rigorous clinical methodology could expand the therapeutic armamentarium for patients with inadequate responses
Abstract: BACKGROUND AND PURPOSE: People with endometriosis report consuming cannabis to manage their endometriosis symptoms, however, its efficacy has not been established in clinical studies. This study aimed to determine the feasibility, acceptability, and safety of two different medicinal cannabis interventions against placebo in people with endometriosis. MATERIALS AND METHODS: A three-armed randomised controlled trial was conducted, comparing the effects of using both inhaled medicinal cannabis using dried flower containing 16 % delta-9-tetrahydrocannabinol (THC) via vaporisation and an oral oil containing 100mg cannabidiol (CBD) per mL together, versus an oral CBD oil alone, versus a taste- and colour-matched placebo oil. The trial aimed to recruit 63 participants (21 per intervention group). Outcome measures included safety and the occurrence of adverse events, and the acceptability and feasibility of recruitment and retention. RESULTS: Overall, 12 participants were randomised to one of three groups, of whom seven withdrew from the study; four completed the study and one was lost to follow-up. Therefore, acceptability and feasibility of recruitment and retention was considered low. There were 10 adverse events reported (two unrelated to cannabis and eight possibly related to cannabis) and two serious adverse events reported (both unrelated to the intervention). CONCLUSION: Despite an urgent need for an evidence-based approach to using cannabis for endometriosis-related pain, our feasibility trial failed to recruit and retain the small intended sample. Failure of the trial was largely driven by two factors: the requirement to abstain from driving, and a high level of participant withdrawal.
? While endometriosis patients commonly self-report cannabis use for symptom management, this feasibility study represents an important first step toward establishing an evidence base in a population with limited treatment options and significant pain burden. The authors appropriately acknowledge the complexity of cannabis research, including challenges with recruitment, standardization of dosing across delivery methods, and the difficulty of maintaining blinding when patients have prior cannabis experience. Several important confounders merit consideration: baseline cannabis use patterns, concurrent pain medications, the episodic nature of endometriosis pain, and heterogeneity in cannabinoid profiles across products. Despite these methodological hurdles, feasibility data from well-designed trials like this are essential for informing larger RCTs and ultimately answering whether specific cannabis formulations offer meaningful analgesia for endometriosis pain compared to current standard therapies. In clinical practice, patients with refractory endometriosis pain who express interest in cannabis should be counseled that evidence remains preliminary, but referring them to practitioners participating in rigorous research
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