Trust your gut: IBS and medical cannabis

Cannabis was rescheduled in the UK on the 1st November 2018 allowing for its medicinal use in a range of settings. Since then, tens of thousands of patients with a wide range of conditions have accessed cannabis-based medicines, mainly through private prescriptions. 

While the National Institute of Health and Care Excellence (NICE) currently only recommends the use of medical cannabis in the treatment of refractory epilepsy, spasticity associated with multiple sclerosis, and chemotherapy-induced nausea and vomiting, the medicines can be prescribed for other conditions in which there is evidence of efficacy, including for IBS.

What is Inflammatory Bowel Syndrome?

Inflammatory Bowel Syndrome (IBS) is the name given to chronic inflammatory conditions, like ulcerative colitis (UC) and Crohn’s disease (CD). It is characterised by episodes of inflammation, alongside other symptoms, primarily affecting the gastrointestinal tract. According to a 2020 baseline population of 16.1 million individuals, IBS/IBD may affect an estimated 0.8%, or over 500,000, people in the UK.

The pathophysiology of IBS is not fully understood; however, it appears to be linked to a dysregulated immune system and an inappropriate inflammatory response. Individuals with UC and CD may experience a range of symptoms, including persistent diarrhoea, abdominal pain, weight loss, malnutrition, and fatigue. IBS is often associated with a decreased quality of life due to symptoms and other burdens linked with the diagnosis.

Conventional treatments for IBS

Patients with Inflammatory Bowel Syndrome will no doubt be desperate to know, “How do you permanently treat IBS?”.  Unfortunately, there is no cure for the conditions. Treatments instead focus on symptom management and maintaining remission of the disease. Conventional therapies mainly work through immune suppression, including aminosalicylates, antibiotics, corticosteroids, immunomodulators, and biologic therapies. 

Despite significant developments in therapies for IBS, management of the condition is often far from satisfactory. In a 2023 narrative review of pharmacological therapy in inflammatory bowel diseases, researchers note that “despite the different mechanisms of action already released for the treatment of CD and UC, many patients remain unable to achieve remission.” 

Furthermore, even in patients who achieve initial clinical response, subsequent secondary loss of response affects up to 40% of patients. Many other patients are also unable to tolerate adverse events associated with conventional IBD therapies, leading to cessation of treatments.

Reports indicate that a growing number of patients are therefore attracted to the use of complementary and alternative medicine for the management of IBS - which begs the question, “Can cannabis help when treating IBS?”

Medical cannabis and IBS

Despite being used as a therapeutic for thousands of years, many areas of clinical cannabis research remain relatively underdeveloped. However, anecdotal evidence suggests that there is an association between cannabis and IBS management. For example, a 2020 survey of Australian IBS patients found that over a quarter (25.3%) of respondents were current or past users of medical cannabis and 92.7% endorsed cannabis as effective in symptom management.

Of the many active compounds found in the cannabis plant, phytocannabinoids (in particular, THC and CBD) have received the most interest in medical research settings. These compounds have been found to interact primarily with the endocannabinoid system (ECS), a system of various receptors, neurotransmitters (endocannabinoids) and enzymes that are expressed throughout the central nervous system and the immune system.

The ECS has been found to play a role in many of the body’s vital processes. Notably, the presence of both cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) in the enteric nervous system suggests the ECS may be critical in the regulation of various gastrointestinal (GI) functions. 

This is supported by multiple studies which indicate activation of the CB1 receptors modulates several functions in the GI tract, including food intake, nausea and emesis, gastric secretion and gastroprotection, GI motility, visceral sensation, intestinal inflammation and cell proliferation in the gut. 

Therefore, the ECS has been implicated as a potential target for future therapeutic approaches to IBS treatments.

Cannabis and IBS - Tackling the symptoms

Similar to the survey of Australian IBD patients mentioned above, a 2013 US population survey found that 12.3% of patients actively used cannabis - many of whom reported its effectiveness in managing symptoms including abdominal pain, poor appetite, and nausea. Some patients from these surveys also indicated that medical cannabis use was useful for co-occurring symptoms, including anxiety, stress, and poor sleep.

 A 2022 analysis of medical cannabis patients from the UK Medical Cannabis Registry also found that initiation of medical cannabis treatment was associated with improvements in IBS-specific and health-related quality of life outcomes.

Furthermore, a 2021 review of 15 non-randomised studies and five randomised controlled trials found that administration of cannabinoids was associated with improvements in clinical symptoms in IBS patients, including abdominal pain, nausea, diarrhoea, and poor appetite, as well as general well-being. However, the review found no evidence of efficacy for inducing disease remission and no effect on inflammatory biomarkers was observed. 

Could CBD help with IBS symptoms?

While there is currently no evidence to support the medicinal use of commercial cannabidiol (CBD) products, some evidence suggests that the common cannabinoid may be beneficial for a number of ailments, including anxiety and sleep disorders. But could CBD help with IBS symptoms?

Few human studies have focused solely on the effects of CBD in IBS; however, in murine models of colitis, CBD has been seen to reduce colon injury and decrease the expression of inflammatory markers associated with the condition. Nonetheless, most positive outcomes observed for medical cannabis treatment of IBS have involved higher doses of THC, a partial agonist of both CB1 and CB2 receptors. 

What type of CBD is best for IBS?

If you are still interested in the potential of CBD for IBS, there are a number of products you can try, including oils, edibles, and vape products. Each of these products has a different route of administration which can also affect the bioavailability (how much of the product is absorbed by the body) of the compound.

Oral administration is by far the most common administration route for products targeting the gastrointestinal tract. This may suggest that oral CBD products such as edibles, capsules, and oils may be the best option for IBS; however, there is no evidence for the effectiveness of these products and commercial CBD products are not recommended for medicinal use. Furthermore, it is always advised that you speak to a qualified healthcare professional before commencing use.

How much CBD should you take for IBS?

Again, a lack of evidence makes it difficult to know what dose of CBD may be best for IBD - or any other condition. It is therefore recommended that you start with a low dose and gradually increase the amount based on your perceived effects. Always ensure that you do not exceed the maximum dosage advised by the product label.

Can cannabis cause gastrointestinal side effects?

While many patients with Inflammatory Bowel Syndrome report significant improvements in their symptoms with medical cannabis use, there are some other considerations to be made. Some studies indicate that cannabis use may also be associated with some gastrointestinal side effects, including nausea, vomiting, and diarrhoea.

A 2024 systematic review found that 12 out of 13 studies examined reported some type of gastrointestinal tract symptoms experienced in medical and/or recreational cannabis users. However, the majority of studies assesses patients who reported chronic recreational use as opposed to the medicinal use of cannabis.

Final Thoughts

As with many things relating to cannabis, the potential of medical cannabis products in the treatment of Inflammatory Bowel Syndrome remains largely under-explored. However, there is a growing body of evidence to support the potential therapeutic benefits of cannabis-based medicines in the management of various IBS-related symptoms, including abdominal pain, nausea, diarrhoea, and loss of appetite.

 Furthermore, real-world evidence suggests that medical cannabis treatment is associated with improvements in health-related quality of life in IBS patients. Overall, the current findings support further research into the potential of medical cannabis for IBS.

In the meantime, patients who are unable to achieve satisfactory results with conventional therapies may be able to receive a medical cannabis prescription for their IBS diagnosis in the UK and a number of other countries around the world.