Can medical cannabis help with the symptoms of endometriosis?

July 27, 2022

Nearly half of the global population gets their period, but for the 176 million living with endometriosis, that time of the month is a completely different story. 

With chronic pain, debilitating cramps, and uncontrollable flow, the usual cocktail of paracetamol, ibuprofen, and heat pads won’t even touch the pain. Add the lengthy waiting times for treatment to the mix, and many patients are left feeling helpless and desperate for effective pain management. 

As research into the cannabis plant evolves, more and more people are finding that cannabis can significantly reduce their chronic pain – and, in the UK, medical cannabis has the potential to transform symptom management for countless people living with endometriosis.

What is endometriosis?

Endometriosis is a chronic condition of the female reproductive system, characterised by abnormal tissue growth outside of the uterus, in the ovaries, fallopian tubes and, in severe cases, within other pelvic structures and the abdomen. 

Symptoms of endometriosis can be hugely debilitating, and typically include:

  • Chronic pelvic pain
  • Severe period cramps
  • Heavy periods
  • Pain during sex
  • Nausea 
  • Fertility issues

The chronic inflammation and severe pain experienced with endometriosis are caused by the shedding of endometrial tissue during menstruation. Unlike the uterine lining, this abnormal tissue has nowhere to escape; it becomes trapped in the pelvic region, causing the area to become inflamed and painful. 

Endometriosis affects 1 in 10 people in the UK yet, on average, it takes 8 years to receive a diagnosis. Although this is primarily because endometriosis symptoms are similar to many other gynaecological conditions, there is also a persistent implicit bias in healthcare which means that women with chronic pain conditions are often not taken seriously. 

Current therapies for symptom management are limited. Treatment typically involves either over-the-counter or prescription painkillers, hormonal therapies, such as contraceptives, or a combination of the two. Others may require surgery to remove the endometriotic tissue, and some patients may even opt for a hysterectomy as a more permanent solution.

In the lengthy wait for a diagnosis, or to avoid the side effects of strong pain medications, many people with endometriosis are now seeking alternative pain relief methods, such as cannabis-based medicines and CBD. In the UK, some patients may also be eligible for a private cannabis prescription.

Can medical cannabis be used to treat endometriosis in the UK?

In 2018, UK law was changed to permit doctors on the General Medical Council’s specialist register to prescribe cannabis-based medicines for a number of qualifying health conditions. Medical cannabis can therefore be considered for the treatment of chronic pain conditions – endometriosis, included – if traditional therapies are ineffective at managing symptoms.  

Medical cannabis and endometriosis: the research

Research into endometriosis is scarce enough as it is, with women’s reproductive health constituting only 2.1% of publicly-funded research. It, therefore, comes as no surprise that research into the effect of medical cannabis on gynaecological pain is even more limited.

That said, several studies have explored the effect of cannabinoids on endometriosis pain. One study, published in PLoS One in 2021, investigated the effects of self-reported cannabis use in 252 participants with endometriosis. Researchers found that concluded that cannabis use improved pain, gastrointestinal symptoms, and mood deficits associated with endometriosis. The study also noted that participants reported a preference for inhalation, such as smoking or vaping, over ingestion of edible cannabis products, which is likely “​​due to the rapid onset of pain-relieving effects,” the authors write. 

A recent review, published in Obstetrics and Gynecology in 2022, analysed data from 16 studies that investigated the effects of cannabis on managing gynaecological pain, such as chronic pelvic pain and endometriosis. The review found that between 61% and 95.5% of participants reported pain relief with cannabis use. The authors note, however, that “interpretation of the studies is limited due to varying…formulations, delivery methods, and dosages” of unregulated cannabis products.

Although the research is scarce, the results are promising. These initial findings, alongside those from other chronic pain studies and countless anecdotal reports, suggest that medical cannabis is likely to be effective at managing endometriosis pain. 

How does it work?

Tetrahydrocannabinol (THC) and cannabidiol (CBD), the two major cannabinoids found in the cannabis plant, are known to activate and modulate CB1 and CB2 receptors throughout our endocannabinoid system (ECS). Surprisingly, both receptor types have been found in the female reproductive system. 

Other research has identified that the ECS plays a prominent role in women’s reproductive health, with endocannabinoid levels contributing to processes related to menstruation and pregnancy. The ECS is also thought to be implicated in endometriosis pain, with one study showing that endometriosis patients exhibit fewer CB1 receptors than healthy subjects, which is thought to be associated with impaired pain control.   

It is believed that cannabinoids could regulate this system and, in turn, reduce endometriosis symptoms. Although the exact mechanisms are still being investigated, it is generally accepted that CBD’s potent anti-inflammatory action and THC’s ability to modulate pain pathways are what help to manage gynaecological pain.  

Is medical cannabis safe?

Understandably, there are some risks and side effects that come with using medical cannabis, as there are with any medication. Though, fortunately, adverse effects are rare with cannabis-based medicines, particularly in comparison to painkillers and hormonal contraceptives. 

The most common side effects of medical cannabis include dizziness, fatigue, dry mouth, appetite changes, and nausea. However, many studies have noted that these are typically resolved with persistent use.  

It is, however, worth noting that there are fewer risks associated with licensed cannabis medicines than with unregulated cannabis products, where there is no guarantee of their quality or contamination with harmful substances.

I think I’m eligible – what next?

In the UK, a patient is unlikely to be prescribed a cannabis-based medicine on the NHS unless they have any of the following conditions:

  • Rare, severe forms of epilepsy
  • Vomiting or nausea caused by chemotherapy
  • Muscle stiffness and spasms caused by multiple sclerosis (MS)

Instead, patients with endometriosis and other qualifying conditions may be eligible for a private prescription through one of the UK clinics. Generally speaking, a patient can be considered for a medical cannabis prescription if two previous treatments have been unsuccessful. 

Costs will vary between clinics, with consultations ranging between £50 and £200, and the average prescription being between £150 and £250 per month. For patients involved in schemes such as Project Twenty21, prescriptions are capped at £150 per product per month in exchange for participating in ongoing studies. 

For more information on the process, take a look at our guide to getting a medical cannabis prescription in the UK.

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