# Cannabis for Endometriosis Pain: Insights from a 2-Year UK Registry > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/cannabis-endometriosis-pain-relief-uk-registry/ > **Published:** 2026-08-11T09:53:28-04:00 | **Last Modified / Clinically Audited:** 2026-09-28T10:47:42-04:00 > **Clinical Summary:** Explore cannabis endometriosis pain relief in a 2-year UK registry study showing significant improvements in pain, quality of life, sleep, and anxiety. --- CED Clinical Relevance #84 Clinical Evidence Update A prospective, 2-year observational analysis of 101 women with endometriosis enrolled in the UK [Medical Cannabis](https://cedclinic.com/therapeutic-benefits-of-thc/) Registry, published 2026 in the Australian & New Zealand Journal of Obstetrics & Gynaecology, found statistically significant improvements from baseline in pain, quality of life, sleep, and anxiety at every follow-up point through 24 months, alongside a measurable drop in prescribed opioid dose. The longitudinal duration, validated outcome measures, and patient-relevant population place it above the newsjack threshold, though its single-arm, non-randomized design keeps it well short of definitive evidence. Clinical Insight | CED Clinic Endometriosis affects roughly 1 in 10 women of reproductive age and routinely causes years of pelvic pain, dyspareunia, and disability, yet a meaningful share of patients continue to have inadequate pain control despite hormonal therapy, NSAIDs, opioids, and surgery. This analysis followed 101 biological females with a primary diagnosis of endometriosis who had been enrolled in the UK [Medical Cannabis](https://cedclinic.com/therapeutic-benefits-of-thc/) Registry for at least two years as of the June 2025 data extraction. Using prospectively collected data, the researchers tracked Brief Pain Inventory (BPI) Severity and Interference, the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2), Pain VAS, EQ-5D-5L health-related quality of life, GAD-7 anxiety scores, and the Sleep Quality Scale (SQS) at baseline and at 1, 3, 6, 12, 18, and 24 months, along with prescribed oral morphine equivalents (OME). Every one of those outcome measures improved significantly from baseline at every single follow-up point (p<0.001), and mean prescribed OME fell from 19.9±17.2 mg/day at baseline to 14.8±15.9 mg/day at 24 months. Eighteen participants (17.8%) reported a combined 165 adverse events, just over half of them (50.9%) mild, with fatigue, lethargy, and headache the most common. The authors themselves conclude that cannabis-based medicinal products (CBMPs) were associated with sustained improvement with a favourable adverse-event profile, and that randomised controlled trials are still required to establish efficacy and safety. Endometriosis[Chronic Pelvic Pain](https://cedclinic.com/cannabis-for-chronic-pelvic-pain-self-management/)[Medical Cannabis](https://cedclinic.com/therapeutic-benefits-of-thc/)UK RegistryWomen’s Health Audience Women living with endometriosis and [chronic pelvic pain](https://cedclinic.com/cannabis-for-chronic-pelvic-pain-self-management/), gynecologists, pain management clinicians, and cannabis clinicians counseling patients on realistic expectations for CBMP use in endometriosis Primary Topic A 2-year prospective observational analysis of cannabis-based medicinal products in 101 women with endometriosis, drawn from the UK Medical Cannabis Registry and published in the Australian & New Zealand Journal of Obstetrics & Gynaecology in 2026 Source [Read the study in ANZJOG](https://doi.org/10.1111/ajo.70173) Table of Contents - [Cannabis for Endometriosis Pain: A 2-Year UK Registry Analysis](#Cannabis_for_Endometriosis_Pain_A_2-Year_UK_Registry_Analysis) - [How to Read a Positive Registry Study Without Overselling It](#How_to_Read_a_Positive_Registry_Study_Without_Overselling_It)[A Four-Step Reading Frame](#A_Four-Step_Reading_Frame) - [The Same Study Can Mean Different Things Depending on the Question Being Asked](#The_Same_Study_Can_Mean_Different_Things_Depending_on_the_Question_Being_Asked)[Encouraging Real-World Data, Not a Guarantee](#Encouraging_Real-World_Data_Not_a_Guarantee) - [A Long-Follow-Up Signal in an Underserved Condition](#A_Long-Follow-Up_Signal_in_an_Underserved_Condition) - [No Control Group Means No Causal Claim](#No_Control_Group_Means_No_Causal_Claim) - [The Opioid Trend Deserves a Careful Read](#The_Opioid_Trend_Deserves_a_Careful_Read) - [Selection and Reporting Bias Are Built Into This Design](#Selection_and_Reporting_Bias_Are_Built_Into_This_Design) - [Name the Clinic Affiliation Plainly](#Name_the_Clinic_Affiliation_Plainly) - [Precise Framing Protects Patient Trust](#Precise_Framing_Protects_Patient_Trust) - [A Case for Funding the Randomized Trial](#A_Case_for_Funding_the_Randomized_Trial) - [Frequently Asked Questions](#Frequently_Asked_Questions)[Related](#Related) ## Cannabis for Endometriosis Pain: A 2-Year UK Registry Analysis A 2-year prospective observational analysis from the UK Medical Cannabis Registry followed 101 women with endometriosis on cannabis-based medicinal products. Pain, quality of life, sleep, and anxiety scores improved significantly at every follow-up point through 24 months, and prescribed opioid dose trended down, but this was a single-arm registry study without a control group, so the improvements cannot be attributed to the cannabis product alone. What This Study Teaches Us This analysis shows that women with endometriosis who stayed enrolled in a structured medical cannabis registry for up to two years reported sustained, statistically significant improvement across multiple validated pain, quality-of-life, sleep, and anxiety measures, alongside a measurable reduction in prescribed opioid dose. It also illustrates, clearly, why an observational before-and-after registry cannot substitute for a randomized controlled trial when the goal is proving that a product caused those changes. Why This Matters Endometriosis is common, frequently disabling, and often undertreated with conventional options alone. A 24-month follow-up with validated outcome measures and a reasonably sized, well-characterized endometriosis-specific cohort is longer and more detailed than most real-world cannabis registry reports, giving clinicians a data point worth understanding, provided its real-world, non-randomized design is represented honestly rather than oversold as proof of efficacy. Study Snapshot Study Type Prospective observational analysis of the UK Medical Cannabis Registry (no control or placebo arm) Population 101 biological females (18 years and older) with a primary diagnosis of endometriosis, enrolled at least 2 years before the June 1, 2025 data extraction Follow-Up Points Baseline, 1, 3, 6, 12, 18, and 24 months Outcomes Measured BPI Severity, BPI Interference, SF-MPQ-2 Total, Pain VAS, EQ-5D-5L Index, GAD-7, Sleep Quality Scale (SQS), and prescribed oral morphine equivalents (OME) Primary Result Statistically significant improvement from baseline in BPI Severity, BPI Interference, SF-MPQ-2 Total, Pain VAS, EQ-5D-5L Index, GAD-7, and SQS at every follow-up point (p<0.001) Opioid Trend Mean prescribed OME decreased from 19.9±17.2 mg/day at baseline to 14.8±15.9 mg/day at 24 months Adverse Events 18 participants (17.8%) reported 165 adverse events; 84 (50.9%) were mild Most Frequent Adverse Events Fatigue (n=16, 15.8%), lethargy (n=15, 14.9%), headache (n=13, 12.9%) Authors’ Conclusion CBMP treatment was associated with sustained improvements in pain, health-related quality of life, sleep, and anxiety at 24 months, with a favourable AE profile. Randomised controlled trials are required to establish efficacy and safety. Journal Australian & New Zealand Journal of Obstetrics & Gynaecology Published 2026, volume 66, issue 4, e70173 DOI 10.1111/ajo.70173 PMID 42576801 Affiliations UK Medical Cannabis Registry, Curaleaf Clinic, Imperial College London Clinical Bottom Line In a 2-year, single-arm registry analysis, 101 women with endometriosis on prescribed cannabis-based medicinal products showed statistically significant improvement in pain, quality of life, sleep, and anxiety at every follow-up point through 24 months, along with a drop in prescribed opioid dose, but without a control group, placebo effect, regression to the mean, and expectation effects remain plausible explanations, and the authors themselves say randomized controlled trials are still required. What the Registry Analyzed Researchers analyzed prospectively collected data from the UK Medical Cannabis Registry for 101 biological females with a primary diagnosis of endometriosis who had been enrolled at least two years before the June 1, 2025 data extraction. Patients were followed at baseline and again at 1, 3, 6, 12, 18, and 24 months, tracking BPI Severity, BPI Interference, SF-MPQ-2 Total, Pain VAS, EQ-5D-5L quality of life, GAD-7 anxiety, sleep quality (SQS), and prescribed oral morphine equivalents. Pain and Quality of Life Improved at Every Checkpoint BPI Severity, BPI Interference, SF-MPQ-2 Total, Pain VAS, and EQ-5D-5L Index all showed statistically significant improvement from baseline at every single follow-up point, from 1 month all the way through 24 months (p<0.001). That consistency across seven separate follow-up windows and multiple validated pain and quality-of-life instruments is one of the more notable features of this dataset for a chronic, often treatment-resistant condition. Sleep and Anxiety Moved in the Same Direction GAD-7 anxiety scores and the Sleep Quality Scale also improved significantly from baseline at every follow-up point (p<0.001), suggesting the reported benefit was not limited to pain measures alone. Endometriosis-related pain, poor sleep, and anxiety commonly reinforce one another, so parallel improvement across all three domains is a coherent pattern, though it does not by itself prove which factor is driving which. Prescribed Opioid Dose Trended Down Mean prescribed oral morphine equivalents fell from 19.9±17.2 mg/day at baseline to 14.8±15.9 mg/day at 24 months, a real-world signal that some patients may have been able to reduce opioid dosing while enrolled in cannabis-based treatment. This is a prescribing trend within an observational cohort, not a controlled opioid-sparing trial, so it should be read as a hypothesis worth testing rather than a demonstrated opioid-reduction effect of CBMPs. Adverse Events Were Common but Mostly Mild Eighteen participants, 17.8% of the cohort, reported a combined 165 adverse events, of which 84 (50.9%) were classified as mild. The most frequently reported were fatigue (n=16, 15.8%), lethargy (n=15, 14.9%), and headache (n=13, 12.9%). That a meaningful minority of patients experienced adverse effects, even when most were mild, is worth naming plainly rather than glossing over in favor of the positive outcome data. Why This Is Not a Randomized Trial This was a single-arm, before-and-after observational analysis with no placebo or control group, no blinding, and outcomes measured entirely through patient-reported instruments. The UK Medical Cannabis Registry operates through Curaleaf Clinic, and several authors are affiliated with that clinic, a relevant disclosure given that the same organization that enrolls, treats, and follows patients also has a commercial interest in favorable outcomes. The authors themselves state that randomised controlled trials are required to establish efficacy and safety. How Strong Is This Evidence? This is a prospectively collected, longitudinal registry analysis with a genuinely long follow-up window, 24 months, and a reasonably sized, diagnosis-specific cohort of 101 women with endometriosis, which is more detailed and more sustained than most real-world cannabis registry reports. The consistency of statistically significant improvement across seven follow-up points and seven separate validated outcome measures (BPI Severity, BPI Interference, SF-MPQ-2, Pain VAS, EQ-5D-5L, GAD-7, and SQS) is a coherent, real-world signal that this population, drawn from patients who chose and stayed on CBMP treatment, reported durable improvement rather than a brief placebo bump that faded within weeks. Where This Paper Deserves Skepticism This was an observational, single-arm registry analysis, not a randomized controlled trial. There was no placebo or control arm, so the reported improvements cannot be causally attributed to the cannabis product alone. Placebo effect, regression to the mean, and expectation effects from committing to a structured cannabis treatment program are all plausible contributors to the improvements seen. All outcomes were patient-reported, there was no blinding, and the population represents patients who selected into and remained in cannabis treatment, which is a very different group from an unselected endometriosis population. The UK Medical Cannabis Registry is run through Curaleaf Clinic, and several study authors are affiliated with that clinic, a financial and institutional conflict-of-interest consideration worth naming honestly rather than minimizing. The authors’ own conclusion states plainly that randomised controlled trials are required to establish efficacy and safety, and that caveat should be taken at face value. What This Paper Does Not Show This analysis does not show that cannabis-based medicinal products caused the reported improvements beyond what placebo, regression to the mean, or the natural waxing and waning course of endometriosis symptoms could explain. It does not show that CBMPs work better than existing endometriosis therapies, since there was no active comparator. It does not establish that the observed decrease in prescribed opioid dose reflects a specific opioid-sparing effect of cannabis rather than broader engagement with a structured pain-management program. It also does not, on the basis of the details provided here, establish long-term safety or efficacy beyond 24 months, or generalize cleanly to patients outside a specialist UK cannabis clinic setting. How This Fits With the Broader Clinical Conversation This registry analysis adds to a small but growing body of real-world CBMP data in endometriosis, joining earlier, shorter cohort reports that also found improvement in pain and quality-of-life measures over shorter observation windows. What this analysis adds is duration, following the same patients out to 24 months rather than weeks, and a broader outcome set that includes anxiety, sleep, and opioid prescribing alongside pain. The next meaningful step, as the study authors themselves note, is a randomized controlled trial with a genuine placebo or active comparator arm, which is the only design capable of separating a true pharmacological effect from the substantial nonspecific benefits that come from structured clinical engagement, expectation, and the natural course of a fluctuating [chronic pain](https://cedclinic.com/cannabinoids-pain-management-opioid-alternative/) condition. Dr. Caplan’s Take *I have been practicing family medicine and [cannabis medicine](https://cedclinic.com/essential-oils-industrial-hemp-antimicrobial-benefits/) for more than 20 years, and this is the kind of dataset I want to see more of for endometriosis: a real cohort followed carefully over two full years, with validated pain, quality of life, anxiety, and sleep measures all moving in the same encouraging direction, plus an opioid dosing trend that matters in daily practice. That consistency across seven follow-up points is not nothing, and for a condition where many patients feel dismissed or run out of good options, this data is worth taking seriously.* *At the same time, I have to be honest about what this study is and is not. It is a single-arm, before-and-after registry analysis with no placebo group, no blinding, and patient-reported outcomes from people who chose to start and stayed on cannabis treatment. That design cannot separate a genuine drug effect from placebo response, regression to the mean, or the simple benefit of feeling cared for by a structured clinic program. The registry runs through a commercial cannabis clinic, which is a conflict of interest worth stating plainly rather than glossing over. I read this as a promising, real-world signal that supports doing the randomized trial the authors themselves call for, not as proof that cannabis treats endometriosis. If a patient of mine with endometriosis asks about this study, I would frame it exactly that way: encouraging, but not yet conclusive.* What a Careful Reader Should Take Away A 2-year observational analysis of 101 women with endometriosis found significant improvement in pain, quality of life, sleep, and anxiety at every follow-up point on cannabis-based medicinal products, along with a drop in prescribed opioid dose, but the single-arm, non-randomized, clinic-affiliated design means these results are a real-world signal in need of confirmation, not proof that the cannabis product itself caused the improvement. Evidence Interpretation Guide ## How to Read a Positive Registry Study Without Overselling It A 2-year dataset with consistent, statistically significant improvement across seven outcome measures can look like strong proof at first glance. Four checks keep this analysis’ real contribution in view without treating an observational registry as a randomized trial. ### A Four-Step Reading Frame **Confirm the design**This was a single-arm, before-and-after observational registry analysis, not a randomized, placebo-controlled trial. **Separate correlation from cause**Improvement after starting treatment is not the same as proof that the treatment caused the improvement. **Weigh the affiliation**The registry runs through Curaleaf Clinic, and several authors are clinic-affiliated, a disclosure that deserves transparency. **Hold the authors’ own caveat**The study authors state directly that randomised controlled trials are required to establish efficacy and safety. The Research Question Do women with endometriosis enrolled in a UK medical cannabis registry show sustained improvement in pain, quality of life, sleep, and anxiety, and a change in prescribed opioid dose, over 24 months? The Patient Question Could staying on a monitored cannabis treatment program help my endometriosis pain, sleep, and anxiety over the long term, even though this evidence is not yet from a randomized trial? The Bottom Line The registry data are encouraging and consistent over two years, but only a randomized controlled trial can show whether the cannabis product itself, rather than the surrounding care, is responsible. CED Perspective Lens ## The Same Study Can Mean Different Things Depending on the Question Being Asked Scientific papers rarely answer a single question. Patients, clinicians, researchers, policymakers, and critics often read the same data differently. The perspectives below explore how this study looks through several evidence-based lenses. Lens Overview Eight perspectives keep a consistently positive registry dataset from being oversold as proof of efficacy or dismissed because it lacks a control group. #### Encouraging Real-World Data, Not a Guarantee If you live with endometriosis, this analysis offers a genuine, 2-year real-world data point showing sustained improvement in pain, sleep, anxiety, and quality of life among women who stayed on cannabis-based treatment. It is not proof that cannabis will do the same for you, and it is not evidence that it works better than other treatments you may already be using or considering. Lens takeaway Treat this as a reason to ask your clinician about it, not as a promised result. #### A Long-Follow-Up Signal in an Underserved Condition Endometriosis patients frequently exhaust hormonal therapy, NSAIDs, opioids, and surgical options without adequate relief, so a 24-month dataset showing sustained improvement across multiple validated measures is clinically relevant context. It should inform a shared-decision conversation about CBMPs as one option among several, not replace guideline-directed endometriosis management. Lens takeaway Useful supporting context for a difficult-to-treat population, not a new standard of care. #### No Control Group Means No Causal Claim Every outcome measure improving significantly is exactly the pattern you would also expect from placebo response, regression to the mean, and the benefit of consistent clinical engagement, none of which this design can rule out. A clinic-affiliated registry publishing favorable results on its own patient population is a combination that calls for extra scrutiny, not automatic skepticism, but scrutiny nonetheless. Lens takeaway Consistent improvement without a control arm is a hypothesis, not a demonstrated effect. #### The Opioid Trend Deserves a Careful Read A drop in mean prescribed OME from 19.9 to 14.8 mg/day over 24 months is clinically interesting, but this cohort was not designed to test opioid-sparing effects specifically, so confounding by broader care engagement is very possible. Pain clinicians should view this as a prompt to study opioid-sparing potential formally, not as evidence that CBMPs directly replace opioid therapy. Lens takeaway A promising trend that needs a controlled study before it changes prescribing practice. #### Selection and Reporting Bias Are Built Into This Design Participants were patients who chose to start and remained enrolled in CBMP treatment for at least two years, a selected group unlikely to represent the full range of endometriosis patients, including those who stopped treatment or had it fail. All outcomes were patient-reported with no blinding, and the source material available for this review did not specify retention or dropout rates, both important gaps for interpreting a 24-month observational cohort. Lens takeaway A selected, unblinded cohort with patient-reported outcomes needs independent replication. #### Name the Clinic Affiliation Plainly The UK Medical Cannabis Registry operates through Curaleaf Clinic, and several study authors are affiliated with that clinic, meaning the organization enrolling, treating, and following these patients also has a commercial interest in favorable outcomes. This does not automatically invalidate the findings, but it is a disclosure that belongs front and center in any honest summary of this evidence, not a footnote. Lens takeaway A commercial cannabis clinic publishing favorable outcomes on its own registry patients is a disclosure worth naming directly. #### Precise Framing Protects Patient Trust Headlines describing this as proof that cannabis treats endometriosis would misrepresent an observational, single-arm registry analysis without a control group. Communicating the actual, more limited finding, sustained improvement in a treated cohort without a comparator, protects patient trust and keeps expectations realistic while the field waits for randomized data. Lens takeaway Report the registry finding accurately rather than generalizing it into a treatment claim. #### A Case for Funding the Randomized Trial No medication is currently approved specifically for endometriosis-related pain through the cannabinoid pathway, so a consistent, long-duration observational signal is a reasonable basis for prioritizing a well-designed randomized controlled trial. The authors’ own call for RCTs should be read as the appropriate and necessary next step, not as boilerplate language attached to an otherwise conclusive study. Lens takeaway This dataset supports funding and running the randomized trial it cannot substitute for. Join the Conversation Have a question about how this applies to your situation? [Ask Dr. Caplan](https://benjamincaplan.com/ask-dr-caplan) Want to discuss this topic with other patients and caregivers? [Join the forum discussion](https://cedclinic.com/interact/discussion-forums/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Physician-Led, Whole-Person Care A doctor who takes the time to truly understand you. Personal care that starts with listening and is guided by experience and ingenuity. Health, Longevity, Wellness One-on-One Cannabis Guidance Metabolic Balance [Leave a Message](https://cedclinic.com/contact/) [Metabolic Care](https://cedclinic.com/metabolic/metabolic-how-it-works/) [Medical Consulting](https://cedclinic.com/book/) [Cannabis Care](https://cedclinic.com/book/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Share this Evidence Watch [X](https://twitter.com/intent/tweet?text=Cannabis+for+Endometriosis+Pain%3A+A+2-Year+UK+Registry+Analysis&url=https%3A%2F%2Fcedclinic.com%2Fcannabis-endometriosis-2-year-registry-uk%2F) [LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcedclinic.com%2Fcannabis-endometriosis-2-year-registry-uk%2F) [BlueSky](https://bsky.app/intent/compose?text=Cannabis+for+Endometriosis+Pain%3A+A+2-Year+UK+Registry+Analysis%20https%3A%2F%2Fcedclinic.com%2Fcannabis-endometriosis-2-year-registry-uk%2F) [Instagram](https://www.instagram.com/drcaplan/) [Substack](https://doctorapprovedcannabis.substack.com/) [RSS](https://cedclinic.com/feed/) Source: [Ahmed T, Erridge S, Clarke E, McLachlan K, Coomber R, Barnes S, Medniuk AD, Guru R, Holden W, Sajad M, Searle R, Usmani A, Rucker JJ, Platt M, Sodergren MH. Cannabis-Based Medicinal Products for Endometriosis: A 2-Year Prospective Analysis From the UK Medical Cannabis Registry. Aust N Z J Obstet Gynaecol. 2026;66(4):e70173. DOI: 10.1111/ajo.70173. PMID: 42576801.](https://doi.org/10.1111/ajo.70173) Related Reading at CED Clinic Continue exploring the evidence [From Pelvic Pain to Pleasure: The Case for Cannabis as Women’s Medicine](https://cedclinic.com/from-pelvic-pain-to-pleasure-the-case-for-cannabis-as-womens-medicine/) A CED review of a Johns Hopkins systematic review on cannabis for gynecologic pain conditions, useful broader context for where cannabis-based options fit for women with limited pharmacologic choices. [Read the women’s medicine review](https://cedclinic.com/from-pelvic-pain-to-pleasure-the-case-for-cannabis-as-womens-medicine/) [Medical Cannabis Was the Only Treatment in the UK for Endometriosis That Touched the Pain](https://cedclinic.com/medical-cannabis-was-the-only-treatment-in-the-uk-for-endometriosis-that-touched-the-pain/) A CED look at a UK patient narrative describing medical cannabis as the only option that meaningfully addressed her endometriosis pain, useful patient-level context alongside this registry’s group-level data. [Read the patient narrative context](https://cedclinic.com/medical-cannabis-was-the-only-treatment-in-the-uk-for-endometriosis-that-touched-the-pain/) [Medical Cannabis RCT for Endometriosis Pain Research](https://cedclinic.com/medicinal-cannabis-endometriosis-trial-feasibility-safety/) A CED review of an Australian feasibility and safety trial testing inhaled THC flower and oral CBD oil against placebo for endometriosis pain, directly relevant to the randomized trial this registry analysis says is still needed. [Read the RCT feasibility context](https://cedclinic.com/medicinal-cannabis-endometriosis-trial-feasibility-safety/) Similar Studies on CEDClinic.com Earlier coverage on closely related evidence When a new paper overlaps with earlier CED Clinic coverage, we preserve the chain instead of hiding the overlap. These links point to older related posts so readers can compare what is new, what is repeated, and how the evidence has moved. Related digest item [What 12 Weeks of Medicinal Cannabis Did for Endometriosis Pain](https://cedclinic.com/medicinal-cannabis-endometriosis-cohort-study/) A 2026 medicinal cannabis endometriosis cohort study found a 31% reduction in pelvic pain and a 46% quality-of-life improvement over 12 weeks. Some patients discontinued opioids during the study. This research offers ne… Covers a closely related topic; this CED post is older by about 99 days and gives earlier context. [Compare earlier coverage](https://cedclinic.com/medicinal-cannabis-endometriosis-cohort-study/) ## Frequently Asked Questions What did this study look at? A prospective, 2-year observational analysis of the UK Medical Cannabis Registry followed 101 biological females with a primary diagnosis of endometriosis, tracking pain, quality of life, sleep, anxiety, and prescribed opioid dose at baseline and at 1, 3, 6, 12, 18, and 24 months. What outcomes improved, and by how much certainty? BPI Severity, BPI Interference, SF-MPQ-2 Total, Pain VAS, EQ-5D-5L Index, GAD-7, and Sleep Quality Scale (SQS) all showed statistically significant improvement from baseline at every single follow-up point, from 1 month through 24 months (p<0.001 at every point). Did prescribed opioid use change? Mean prescribed oral morphine equivalents (OME) decreased from 19.9±17.2 mg/day at baseline to 14.8±15.9 mg/day at 24 months, a real-world prescribing trend rather than a result from a controlled opioid-sparing trial. Was this a randomized controlled trial? No. This was a single-arm, observational registry analysis with no placebo or control group and no blinding. The study authors themselves state that randomised controlled trials are required to establish efficacy and safety. Why does the lack of a control group matter? Without a placebo or comparison group, the reported improvements cannot be causally attributed to the cannabis product alone. Placebo effect, regression to the mean, and expectation effects from structured clinical engagement are all plausible alternative explanations. How many participants had side effects, and how serious were they? Eighteen participants, 17.8% of the cohort, reported a combined 165 adverse events, and just over half (84, or 50.9%) were classified as mild. The most frequent were fatigue (15.8%), lethargy (14.9%), and headache (12.9%). Is there a conflict of interest in this study? Yes, worth naming plainly. The UK Medical Cannabis Registry operates through Curaleaf Clinic, and several study authors are affiliated with that clinic, meaning the organization enrolling and treating these patients also has a commercial interest in favorable results. How does this compare to earlier, shorter endometriosis cannabis cohort studies? This analysis follows patients for up to 24 months, considerably longer than earlier shorter cohort reports, and adds anxiety, sleep, and opioid-prescribing outcomes alongside pain and quality-of-life measures, though it shares the same observational, non-randomized limitations as those earlier studies. What does this study not prove? It does not prove that cannabis-based medicinal products caused the improvements beyond what placebo response or the natural course of endometriosis symptoms could explain, and it does not show that CBMPs work better than existing endometriosis therapies, since there was no active comparator in the design. What should someone with endometriosis take away from this? This is encouraging real-world, long-duration data worth discussing with a treating clinician as one option among several, not proof that cannabis treats endometriosis. A randomized controlled trial, which the authors themselves call for, is the next step needed to establish efficacy and safety. ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), Former CMO Canna Care Docs (250,000+ patients supervised), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House). - **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`). - **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/). - **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637). - **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).