Living with endometriosis can mean pain on most days of the month. For many people, current treatments help only partly, or only for a while. Researchers are now asking whether medicines made from cannabis have any role. Good evidence is still scarce.
A small study published in PLOS One in September 2026 followed 27 women with endometriosis in Berlin, Germany. Each took an oral cannabis extract alongside their usual treatment for 3 months.
Key Takeaways:
- The study. Researchers in Berlin gave 30 women with endometriosis an oral extract containing similar amounts of THC and CBD, two compounds found in cannabis. Of these, 27 completed 3 months of treatment.
- Who took part. Everyone had long-term pelvic pain that had not responded well enough to hormone treatment and painkillers.
- Pain. Average pain scores fell from 6.8 to 4.9 out of 10 over 3 months. The number of days with pain and the number of days needing painkillers also fell.
- Wider wellbeing. Participants reported less tiredness and less anxiety. Scores improved in every area of a questionnaire about living with endometriosis.
- Side effects. Nearly everyone reported at least one side effect. Tiredness and problems with concentration and memory lasted longest. Most side effects were rated as mild. One person stopped early because of side effects.
- What it cannot show. There was no comparison (placebo) group, and everyone knew what they were taking. The study cannot show that the extract caused the changes. The authors say larger randomised trials are needed.
What is endometriosis?
Endometriosis is a long-term (chronic) condition. Tissue similar to the lining of the womb grows in other places, mostly inside the pelvis. It can affect the ovaries, fallopian tubes, the outside of the womb and nearby organs such as the bowel and bladder.
It affects around 1 in 10 women of reproductive age. Common symptoms include:
- pelvic pain, which is often worse around a period
- pain during or after sex
- pain when going to the toilet
- bowel or digestive problems
- tiredness (fatigue)
- difficulty getting pregnant, for some people
Endometriosis can also affect mood, work and relationships. Its exact cause is not known.
How is endometriosis usually treated in the UK?
There is no cure for endometriosis. Treatment aims to ease symptoms and improve daily life. The National Institute for Health and Care Excellence (NICE) guideline on endometriosis covers the main options:
- Pain relief. NICE suggests doctors consider a short trial of paracetamol or an anti-inflammatory painkiller (NSAID), such as ibuprofen.
- Hormone treatments. These include the combined contraceptive pill or a progestogen. Specialists may use other hormone treatments if these do not help.
- Surgery. An operation to remove areas of endometriosis may be offered, for example if other treatments have not helped or fertility is affected.
These treatments do not help everyone enough. A large review of 58 studies found that many women get only limited or short-lived relief from medicines. Long-term use of some painkillers also carries risks. NSAIDs can affect the stomach, kidneys and heart. Opioid painkillers can cause dependence and other side effects.
Your GP or gynaecology team can talk you through which options may suit you.
Why are researchers studying cannabinoids for endometriosis?
Many people with endometriosis look for their own ways to manage symptoms. One online survey asked 912 people with endometriosis in Germany, Austria and Switzerland how they managed their symptoms. Of these, 114 said they used cannabis. Surveys like this show what people are doing. They cannot show whether cannabis works.
Cannabis contains compounds called cannabinoids. The two most studied are THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol). They act on the endocannabinoid system. This is a network of receptors and signalling molecules in the body. It helps to regulate pain, inflammation, mood and sleep.
Laboratory and animal studies suggest the endocannabinoid system may be involved in endometriosis. These early findings do not show that cannabinoids help people with endometriosis. The studies in humans are still too small and not of high enough quality.
What did this study do?
This was a pilot study. A pilot study is a small, early study. It tests whether a larger study is possible and gives a first look at possible effects and side effects.
The study took place at the Endometriosis Center at Charité university hospital in Berlin. Between November 2023 and May 2025, 30 women joined. For each of them, a doctor had already recorded a medical reason to try a cannabis-based medicine.
Who could take part?
To join, women had to:
- be aged 18 to 48 and not yet through the menopause
- have endometriosis confirmed by medical records, surgery or tissue tests
- have had ongoing pelvic pain for at least 3 months, not only around their periods
- rate their pain as 4 or more out of 10 on average
People could not take part if they:
- had heart disease
- were pregnant, breastfeeding or planning a pregnancy
- had used cannabis regularly in the past 6 months
- had started or changed hormone treatment in the 3 months before the study
- had a known addiction
- often drove or operated heavy machinery
- were taking part in another clinical trial
What treatment did participants receive?
Everyone took an oral cannabis extract with similar amounts of THC and CBD. It was added to their usual treatment. Hormone treatments and other medicines were not changed as part of the study.
The dose was increased slowly over 4 weeks to a fixed daily dose, taken twice a day. The research team phoned each participant at 2 and 4 weeks. They checked for side effects and adjusted the dose if needed. Doses then stayed broadly the same for the rest of the study.
What did the researchers measure?
Participants filled in online questionnaires before treatment and after 1, 2 and 3 months. These covered:
- pain intensity, on a scale from 0 (no pain) to 10 (worst pain)
- days with pain, and days on which they needed painkillers
- tiredness, using the Chalder Fatigue Scale
- anxiety, using the GAD-7 questionnaire
- central sensitisation, using the Central Sensitization Inventory. Central sensitisation is when the nervous system becomes more sensitive, so pain is felt more strongly or more widely.
- how much pain limits daily life, using the Pain Disability Index
- quality of life, using the Endometriosis Health Profile-30 (EHP-30). This questionnaire was designed for people with endometriosis.
- side effects
The main goal was a fall of at least 15 points in the pain section of the EHP-30 after 3 months.
Who took part?
The 27 women who completed the study had an average age of 33. Their history shows how hard their pain had been to manage:
- 22 of 27 (81.5%) were using a hormone treatment
- all had had at least one operation for endometriosis, and 13 of 27 (48.1%) had had two or more
- nearly all had used NSAIDs, and 7 of 27 (25.9%) were taking opioid painkillers when the study began
Most had also tried approaches that do not involve medicines. Around 9 in 10 had changed their diet (24 of 27) or tried yoga (24 of 27). Many had tried osteopathy (23 of 27) or physiotherapy (20 of 27). Participants said diet changes, physiotherapy and structured rehabilitation gave them the most meaningful improvement.
Most had little experience of cannabis. Ten (37.0%) had never used it, and 12 (44.4%) had tried it only many years before. None used it regularly.
What did the study find?
Did pain outcomes change?
Yes. Average pain scores fell during treatment, from 6.8 prior to treatment starting to 4.8 at 3 months.
The number of days with pain also fell. Before treatment, the typical participant had pain on 30 days a month. This fell to 20 days at 2 months and 17 days at 3 months. These figures are medians. The median is the middle value when everyone’s results are put in order.
The number of days on which participants needed painkillers also fell. This change was seen from the first month.
The researchers had set a fall of 15 points in the EHP-30 pain section as their main goal. On average, this score fell by about 21 points, from 59 to 38.
These are group averages from a small study with no comparison group. Some people improved more than others, and some may not have improved at all.
Were there any changes in the other outcomes?
The EHP-30 scores each area of life from 0 to 100. A lower score means endometriosis has less impact on quality of life. Average scores were lower in every area after 3 months. After 3 months, participants also reported:
- less tiredness
- less anxiety
- lower central sensitisation scores
- less interference from pain in daily life, work and social activities
What side effects were reported?
Side effects were common. The authors report that nearly all participants had at least one side effect during the study.
Participants rated each side effect from 0 (none) to 3 (severe) at each time point. Most were rated 0 or 1. The researchers describe a score of 1 as mild. This means noticeable, but not distressing and not limiting daily life.
Reported side effects included:
- Tiredness, poor concentration and memory problems. These lasted longest, affecting around 60% of participants throughout the study.
- Nausea. This affected 8 of 27 (29.6%) at 1 month, falling to 4 of 27 (14.8%) at 3 months.
- Changes in appetite. These affected between 11 and 15 of 27 participants (40.7% to 55.6%) at each time point. Body weight was not measured.
- A faster heartbeat. This affected 5 of 27 (18.5%) at 1 and 2 months, and 3 of 27 (11.1%) at 3 months.
- Anxiety or panic. This fell from 26% to 4% of participants over the study.
- Paranoia, which means feeling suspicious or threatened without good reason. This fell from 4% of participants to none.
One woman stopped treatment during the first 4 weeks because of side effects. She is not included in the results above.
People with heart disease or a history of addiction could not take part. Nor could people who were pregnant or breastfeeding. So the study cannot tell us about side effects in these groups. Three months is also too short to show longer-term effects.
What are the limitations of this study?
The authors point out several important limits:
- Small size. Only 27 women completed the study, all at one hospital.
- No comparison group. There was no placebo group. A placebo is a dummy treatment with no active ingredient. Without one, it is not possible to tell how much of the change was due to the extract.
- Everyone knew what they were taking. Hopes and expectations can affect how people rate their symptoms. This is especially likely when people have already tried many treatments.
- Self-reported results. All outcomes came from questionnaires that participants filled in themselves.
- Who took part. Participants joined because their doctors already felt a cannabis-based medicine was an option. They may not represent everyone with endometriosis.
- Short follow-up. Three months cannot show long-term benefits or harms. Long-term THC use can lead to tolerance, which means needing more for the same effect. It can also cause withdrawal symptoms on stopping. Effects on memory, hormones and other body systems in women of reproductive age are not yet well understood.
Pain in long-term conditions also goes up and down naturally. People often join studies when their symptoms are at their worst, so some improvement may happen anyway.
How does this study fit with other research?
Only a few studies have followed people with endometriosis taking a prescribed cannabis-based medicine.
- A 2-year UK study. An analysis of the UK Medical Cannabis Registry followed 101 women prescribed cannabis-based medicines for endometriosis. Patients reported improvements in pain, quality of life, sleep and anxiety. This study also had no comparison group (Ahmed et al., 2026).
- A small Australian trial. This trial compared cannabis products with a placebo in people with endometriosis. It could not recruit and keep enough participants to answer whether the treatments worked (Chesterman et al., 2025).
To our knowledge, no large randomised controlled trials of cannabis-based medicines for endometriosis have yet been published.
What to do with this information?
This study adds early information about an oral THC and CBD extract used alongside usual care for endometriosis. Over 3 months, participants reported less pain, fewer pain days, fewer days needing painkillers and better quality of life. Side effects were common but mostly mild.
It does not show that cannabis-based medicines treat endometriosis, or that they are right for any one person. Without a comparison group, the changes cannot be put down to the extract with confidence. The authors call for larger randomised controlled trials with longer follow-up. These would test whether these medicines help, which dose is best, and how safe they are over time.
The study also shows that many participants valued approaches that do not involve medicines, such as physiotherapy and diet changes. The authors suggest these may play an important part in endometriosis care.
Frequently asked questions
Can medical cannabis cure endometriosis?
No. There is no cure for endometriosis. Treatment focuses on easing symptoms. Research into cannabis-based medicines for endometriosis is at an early stage.
What did this pilot study find?
The study followed 27 women with endometriosis who took an oral THC and CBD extract alongside usual treatment for 3 months. Average pain scores fell from 6.8 to 4.9 out of 10. Quality-of-life scores improved in every area measured. There was no comparison group, so the study cannot show that the extract caused these changes.
What side effects were reported?
The authors report that nearly all participants had at least one side effect. Tiredness, poor concentration and memory problems lasted longest, affecting around 60% of participants. Most side effects were rated as mild. One person stopped early because of side effects.
What does NICE say about cannabis and endometriosis?
NICE’s endometriosis guideline (NG73) does not include cannabis-based medicines. NICE’s guideline on cannabis-based medicinal products (NG144) covers chronic pain in adults. It advises doctors not to offer THC, or THC combined with CBD, for this on the NHS. It advises that CBD alone should only be offered for chronic pain as part of a clinical trial.
Is medical cannabis legal in the UK?
Yes. Since November 2018, specialist doctors in the UK have been able to prescribe cannabis-based medicines when other treatments have not worked well enough. Most of these medicines are unlicensed. They are only available on prescription after a specialist assessment.
Who carried out and funded the study?
Researchers at the Endometriosis Research Centre at Charité in Berlin carried out the study. It received no specific funding, and the authors declared no competing interests. The cannabis extract was provided by its manufacturer. Curaleaf Clinic was not involved.
Thinking about your treatment options?
If endometriosis pain is affecting your life, speak to your GP or gynaecology team first. They can review your current treatment and talk you through your options. The charity Endometriosis UK also offers support and information.
In the UK, cannabis-based medicines are prescription-only and unlicensed for endometriosis. A specialist doctor may consider them only after a full assessment, usually when licensed treatments have not helped enough. To find out whether a specialist consultation may be appropriate for you, you can complete Curaleaf Clinic’s online eligibility check. Any decision about treatment is made by a specialist doctor on an individual basis.
