Clinical Takeaway
Researchers attempted a three-armed randomized controlled trial comparing inhaled THC-dominant cannabis, an oral cannabis oil, and placebo for endometriosis pain, but encountered significant feasibility challenges that limited their ability to draw conclusions about efficacy. While many patients with endometriosis already self-report using cannabis for symptom management, this study highlights that conducting rigorous clinical trials in this area faces practical barriers that must be addressed before evidence-based recommendations can be made.
#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 currently use cannabis off-label for symptom management despite lack of clinical evidence, creating a clinical evidence gap that this feasibility trial addresses through rigorous RCT methodology. Establishing the feasibility and safety parameters of medicinal cannabis interventions in this population is essential before larger efficacy studies can be appropriately designed and powered. This work provides critical preliminary data to inform whether cannabis represents a viable pharmacological option for endometriosis pain management within evidence-based clinical practice.
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 this feasibility study addresses an important gap in understanding cannabis for endometriosis pain, several limitations warrant careful consideration before clinical application. The trial’s incomplete abstract and focus on feasibility rather than efficacy means we lack definitive evidence about whether cannabis actually improves endometriosis symptoms compared to placebo. Endometriosis patients are already self-medicating with cannabis, suggesting real symptom burden and potential demand, yet confounders such as concurrent pain treatments, variable cannabis potency and cannabinoid profiles, patient selection bias, and the challenge of adequate placebo blinding in inhaled studies could obscure true treatment effects. Additionally, the Australian regulatory and product standardization context may not directly translate to other jurisdictions where patients face different legal and access barriers. In clinical practice, until larger efficacy trials are complete, we can acknowledge patient interest and existing self-use patterns while being transparent about the evidence gap, helping patients understand that cannabis for endometriosis remains a therapeutic option worthy of study rather than an established standard of care.