What endometriosis is
Endometriosis is a chronic inflammatory condition in which tissue similar to the lining of the uterus grows outside the uterus — most commonly on the ovaries, fallopian tubes, and pelvic peritoneum. It affects roughly one in ten women and people assigned female at birth of reproductive age, though diagnostic delay averages seven to ten years. The main symptoms are severe pelvic pain, painful menstruation, pain during intercourse, and in some cases reduced fertility. The condition is oestrogen-dependent and involves immune dysfunction, inflammation, and nerve infiltration in the lesions. Standard treatments include hormonal suppression, surgery, and pain management, but many patients report inadequate relief from available options.
Cannabis research on Endometriosis
The published evidence on cannabis and endometriosis comes predominantly from patient surveys. No randomised controlled trial of cannabis for endometriosis has been published.
A 2022 international cross-sectional survey of 1,634 people with diagnosed endometriosis from 46 countries, published by Armour and colleagues, found that 51% had used cannabis in the previous three months and 55% of those used it solely for symptom management. Legal access was significantly associated with higher use. During the COVID-19 pandemic, 57% of users reported increased consumption, with the most common reasons being increased stress and anxiety (59%) and reduced access to normal medical care (48%). Before the pandemic, 61% used cannabis at least once daily and 51.6% used inhalation as the primary route.
A 2021 retrospective study by Sinclair and colleagues analysed 16,193 self-reported usage sessions from 252 people with endometriosis using a cannabis-tracking app. Inhalation was the most common route (67.4% of sessions) and pain was the most frequently treated symptom (57.3%). Gastrointestinal symptoms, though reported less often (15.2% of sessions), showed the greatest self-reported improvement after cannabis use. Inhaled forms were associated with better pain relief scores, while oral forms were preferred for mood and gastrointestinal symptoms. The median dose recorded was 9 inhalations (IQR 5-11) for inhaled products and 1 mg/mL (IQR 0.5-2) for oral forms. The THC:CBD ratio had a statistically significant but clinically small differential effect on symptom relief.
A 2024 online survey of German-speaking people with endometriosis, by Jasinski and colleagues, gathered 912 responses, of whom 114 used cannabis for self-management. Self-rated symptom relief averaged 7.6 out of 10. Around 90% of cannabis users reported they were able to reduce their pain medication intake. The largest reported improvements were in sleep (91%), menstrual pain (90%), and non-cyclic pain (80%). Side effects were uncommon aside from increased fatigue (17%). Cannabis was ranked as the most effective self-management strategy among all options surveyed, despite its illegal status at the time in those countries.
On the biological side, CB1 and CB2 cannabinoid receptors are expressed in endometrial tissue. A 2019 narrative review by Luschnig and Schicho described the presence of the endocannabinoid system in the female reproductive tract and proposed that dysregulation of this system may contribute to endometriosis and other gynaecological disorders. A 2022 literature review by Mistry and colleagues screened 264 articles, included 41, and found that most evidence came from laboratory models with conflicting results. The review stated that there is a shortage of well-designed, robust studies and randomised controlled trials, and noted that UK national guidance cannot recommend cannabis-based products for endometriosis because clear evidence of benefit is lacking.
Compounds studied for Endometriosis
THC acts on CB1 receptors, which are present in the central nervous system and in peripheral tissues including the uterus. In human survey studies of endometriosis, THC-containing cannabis products are the most commonly reported form used for pain. The mechanism may involve modulation of pain signalling pathways, but this is based on general pain research, not endometriosis-specific trials.
CBD does not produce intoxication and interacts with multiple receptor systems beyond CB1 and CB2, including TRPV1 and serotonin receptors. In survey data, a subset of endometriosis patients use CBD-dominant products. The 2022 Mistry review noted that preclinical data on CBD for endometriosis is conflicting and that no RCT has tested CBD specifically for endometriosis pain.
CBG has been studied in preclinical models for its interaction with alpha-2 adrenergic receptors and TRP channels, both of which are relevant to pain and inflammation. No human trial has tested CBG for endometriosis or pelvic pain.
Beta-caryophyllene is a dietary terpene found in black pepper, cloves, and some cannabis varieties. It is a selective CB2 receptor agonist. Since CB2 receptors are expressed on immune cells and in endometrial tissue, CB2 activation is a biologically plausible anti-inflammatory pathway, but this remains at the laboratory research stage for endometriosis.
Myrcene has been studied in animal models for analgesic and muscle-relaxant effects. These findings are preclinical and not specific to pelvic pain or endometriosis.
Linalool has shown anxiolytic and analgesic effects in animal studies. No human data for endometriosis exists.
Limits of the evidence for Endometriosis
No randomised controlled trial of cannabis for endometriosis was found in the cited literature. All human data comes from cross-sectional surveys and a retrospective app-based study, which carry selection bias: people who use cannabis and find it helpful are more likely to participate in cannabis-focused surveys. Self-reported symptom improvement does not equal clinically verified treatment effect. The absence of a placebo control means observed improvements could reflect expectation effects, natural symptom fluctuation, or concurrent use of other treatments.
The biological rationale — that the endocannabinoid system is present in endometrial tissue and may be dysregulated in endometriosis — is based on laboratory and tissue studies. This establishes plausibility but does not establish that administering cannabinoids to a person with endometriosis produces a therapeutic effect.
The 2022 review by Mistry and colleagues is explicit: UK national guidance cannot recommend cannabis-based products for endometriosis because clear evidence of benefit is lacking. The survey data from Australia, Canada, and German-speaking countries shows that a proportion of patients with endometriosis choose to use cannabis and report benefit, but this is patient-reported observational data, not clinical trial evidence.
Sources
1. Armour M, et al. Endometriosis and cannabis consumption during the COVID-19 pandemic: an international cross-sectional survey. Cannabis Cannabinoid Res. 2022;7(4):473-481. Study record 2. Sinclair J, et al. Effects of cannabis ingestion on endometriosis-associated pelvic pain and related symptoms. PLoS One. 2021;16(10):e0258940. Study record 3. Jasinski T, et al. Cannabis use in endometriosis: the patients have their say — an online survey for German-speaking countries. Arch Gynecol Obstet. 2024;310(2):909-918. Study record 4. Luschnig P, Schicho R. Cannabinoids in gynecological diseases. Med Cannabis Cannabinoids. 2019;2(1):29-37. Study record 5. Mistry M, et al. Cannabidiol for the management of endometriosis and chronic pelvic pain. J Obstet Gynaecol. 2022;42(6):1639-1646. Study record
