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Medical Cannabis and CBD for GI Disorders: More Than a Gut Feeling

In recent years, there has been growing interest in the use of medical marijuana for gastrointestinal (GI) disorders.

Research studies have found that up to 15% of patients suffering from GI disorders actively use medicinal cannabis for symptomatic relief, the majority of whom felt that marijuana was “very helpful” for their symptoms.

Conventional therapy for severe GI disorders may not always work well and will often have serious side effects. For some people, cannabis may be a suitable alternative when conventional treatments have failed to provide relief.

Cannabis for GI Disorders: A Quick Summary

  • Medicinal cannabis works on our body via the endocannabinoid system (ECS), a complex cell-signaling system. The ECS consists of cannabinoid receptors found throughout our body.

  • There is a high number of cannabinoid receptors in the digestive system. This makes it a promising therapeutic target against various gastrointestinal disorders.

  • Current treatment options for severe GI disorders, such as inflammatory bowel disease (IBD), often have side effects that may lead to patients stopping treatment.

  • Medicinal cannabis may be a suitable treatment option for patients who find conventional therapy to have reduced or lack of efficacy over time.

How Marijuana Affects Us: The Endocannabinoid System

Cannabis (marijuana), derived from the cannabis sativa plant, is one of the earliest plants cultivated by humans.

It has been used extensively in the past for various conditions, including GI disorders. The most common cannabinoids used in medicinal cannabis products are CBD (cannabidiol) and THC (delta-9-tetrahydrocannabinol).1

Cannabinoids act on two types of receptors in our body: the cannabinoid type 1 receptor and the cannabinoid type 2 receptor. There is a high number of these receptors located in the digestive system.2

Cannabinoid receptors are found throughout the body including the digestive system.

Research on Cannabinoids and the Digestive Tract

There is ongoing interest and research development in the therapeutic potential of cannabis in treating GI disorders. Cannabis has increasingly been used for the treatment of GI disorders such as abdominal pain and diarrhea and studies show it affects many processes in the GI tract via the endocannabinoid system.

Direct or indirect activation of cannabinoid receptors in the GI tract can lead to:4

  • reduced gastric and intestinal secretion.

  • control of intestinal sensitivity

  • reduced pain sensations

  • reduced activity of local immune system, resulting in the lowering of inflammatory responses

In addition, research shows that levels of anandamide, an endocannabinoid, are much lower in the inflamed gut mucous lining of patients with IBD compared to those with healthy gut tissue.5

This presents a promising therapeutic target against various GI disorders, including IBD and irritable bowel syndrome (IBS).

The role of cannabis is not just limited to its effects on the gut, liver, and pancreas, but can extend to other GI symptoms such as nausea and vomiting, anorexia, weight loss, and chronic abdominal pain.1

GI Woe: What Are Gastrointestinal Disorders?

GI disorders, or “tummy problems”, are disorders of the digestive system. The digestive system is an extensive and complex system that breaks down food. This allows us to take in nutrients, minerals, and vitamins for our body, while removing unabsorbed waste at the same time.6

Some digestive problems may be minor and relatively common, such as stomach aches, diarrhea, and constipation. However, there are some GI disorders that may be serious and debilitating, like IBS, Crohn’s disease, and ulcerative colitis (UC). These GI disorders may have a significant impact on a person’s quality of life.7

Irritable Bowel Syndrome (IBS)

IBS affects the colon (large bowel). Although it is not life-threatening, it can be very uncomfortable in some people. Symptoms of IBS include:7

  • abdominal pain or discomfort

  • bloating

  • irregular bowel habits, such as long-term diarrhea or constipation, or alternating between the two

While the causes for IBS aren’t clear, certain things can trigger IBS symptoms in some people. Common triggers include diet, stress, infection, and certain medicines.7

Crohn’s Disease

Crohn’s disease is an inflammatory bowel disease (IBD) that causes painful swelling and redness (inflammation) in the GI tract. It can affect any part of the GI tract, from the mouth to the anus.

Although inflammation is a normal part of our immune system, a problem with the immune system in Crohn’s disease causes continuous inflammation that damages the walls of the GI tract. Common symptoms of Crohn’s disease include:7

  • diarrhoea

  • abdominal pain and cramping

  • fatigue

  • reduced appetite

  • weight loss

Crohn’s disease may be caused by a combination of genetic, environmental and infectious factors that may cause a problem with the immune system, leading to inflammation of the bowel.7

Ulcerative Colitis (UC)

UC, sometimes referred to as simply “colitis”, is an IBD that causes painful swelling and redness in the GI tract. It differs from Crohn’s disease in that it only affects the large bowel (colon and/or rectum), and the inflammation only appears on the surface layers of the bowel lining rather than the entire thickness of the bowel wall.

Symptoms vary between individuals and come and go over time, as inflammation flares up or ease. Symptoms include:7

  • blood and mucus in stool from the bleeding of ulcers formed in the bowel.

  • diarrhea due to less water absorption from the inflamed bowel

  • fatigue

  • reduced appetite

  • weight loss

Like Crohn’s disease, it may also be caused by a mix of genetic, environment and infectious factors that may cause a problem with the immune system, leading to inflammation of the bowel.7

Current Treatment Options for GI Disorders

For some conditions like IBD, current treatment options are not effective in all patients, while patients who do respond to treatment often lose response over time.

In many cases, symptoms persist even when inflammation is controlled. Some patients even experience adverse effects that lead to them stopping treatment.9

Medical cannabis can be considered a suitable alternative in these cases where first line treatments have failed.10

Prevalence of Cannabis Use for GI Disorders

A significant proportion of patients with IBD use complementary and alternative medicine (CAM) for additional management of symptoms. The reasons for seeking out CAM include:12

  • reduced or lack of efficacy of current treatment.

  • fewer side effects

  • a sense of gaining control over the disease

Population studies have reinforced the use of medicinal cannabis for symptom relief in patients with IBD.

Studies found that between 10- 15% of patients with IBD actively use medicinal cannabis or its derivatives. A significant proportion of patients reported symptomatic relief of abdominal pain, diarrhea, and poor appetite.12

Most patients in these studies currently receive treatment at specialized or dedicated IBD clinics, which suggests that they have poor control of these symptoms despite use of current therapies. Medicinal cannabis was found to be of symptomatic benefit to these patients who aren’t responding to current treatment.12

Evidence Snapshot: What Does the Research Say?

While more research is needed to better understand how and why cannabis works, it is relatively safe under the care of a qualified doctor.

Cannabis Role for Irritable Bowel Syndrome

As IBS is characterized by disturbances in GI mobility (diarrhea, constipation, or a combination of both)7, modulation of the endocannabinoid system might be beneficial for IBS patients. Cannabis may help with pain relief and modulation of intestinal motility.

Cannabis Role in Inflammatory Bowel Disease (Crohn’s Disease and UC)

A study in 2012 investigated the benefits of cannabis in 292 patients with IBD.

More than half of the participants had used cannabis in the past or were using it at the time of the study.

For those who used it for symptom control, a majority felt that it was helpful for relief of abdominal pain, nausea, and diarrhoea.15

A 2016 study reviewed the role of cannabinoids in inflammation and GI mucosal defense.

Direct activation of the cannabinoid type 1 receptor helped reduce gastric acid secretion and gastric motor activity.

The process also decreased the formation of gastric mucosal lesions induced by alcohol and stress.

As such, cannabis may be a promising treatment option for IBD, gastric mucosal lesions, ulcers, and inflammation.20

IBD = inflammatory bowel disease; CD = Crohn’s disease; UC = ulcerative colitis; THC = delta-9-tetrahydrocannabinol; CBD = cannabidiol

A meta-analysis of 146 patients from non-randomised studies and randomised trials looked at the safety and efficacy of cannabis in IBD.

Although there was limited efficacy in inducing remission of disease, there were significant differences in disease activity compared to placebo, as well as improvement in symptoms and quality of life.27

Further clinical trials are needed to determine cannabis’ potential as a treatment option for IBD and to guide prescribing decisions.

Cannabis Role in Constipation

Constipation impacts the frequency of bowel movements, or GI motility. A 2005 study found that CBD may help regulate GI movement.28

Cannabis Role in Nausea and Vomiting

A 2011 study found that cannabinoids may help regulate nausea and vomiting. Evidence suggests that cannabinoids may be useful in treating more difficult to control symptoms of nausea in cancer patients, which are poorly controlled by currently available treatment options.29

Cannabis Role in Other GI Symptoms

Cannabis seems to be universally effective at treating symptoms of abdominal pain. This can be especially useful for patients who are taking opioids for abdominal pain. Studies have shown that cannabis can help patients taper down or cease opioid medicines and offer a treatment option with fewer adverse effects.5

The Cannabis Underbelly: Is It Safe to Take?

The long-term safety of cannabis in patients with IBD has not been established. Common side effects from current studies include:10

  • headache

  • sleepiness

  • nausea

  • dizziness

However, it is important to note that current options for IBD management, including steroids and immunosuppressants carry risks for long-term side effects such as malignancy and infection.12

Use of cannabis in clinical therapy has been strongly limited by their psychotropic effects, typically seen with THC. However, CBD is very promising as it shares the typical cannabinoid beneficial effects on the GI tract without the psychotropic effects.30

Medicinal cannabis has no overdose potential. There have not been any reported deaths resulting solely from cannabis use.31

Cannabis for GI Dosing: How Much Can I Stomach?

There is no established or recommended dose for cannabis (both CBD and THC) in managing GI disorders.32

A 2020 systemic review of CBD doses from 20 to 250 mg/day for various indications, for treatment duration from 8 to 13 weeks, were well tolerated, with only mild side effects.33

Table 4 below summaries the different doses of CBD and THC that have been evaluated for Crohn’s disease and ulcerative colitis.

Combination products with both CBD and THC may have the greatest symptom benefits in terms of inflammation. This is because while THC activates cannabinoid type 1 receptors, both CBD and THC have a synergistic effect on cannabinoid type 2 receptors. Studies have shown that both CBD and THC improve symptoms of IBD.34 Taking CBD together with THC is beneficial as studies show that CBD may lesson or reverse some of the negative side effects associated with THC.5 Patients should start cannabis products at the lowest possible dose, especially in products containing THC, monitor carefully for adverse effects and increase slowly over days or weeks to determine if the treatment is effective.35 Contact your doctor if you experience any medicine-related side effect or adverse event. What Should Patients and Caregivers Know?

  • Discuss your treatment options with your doctor before starting treatment with medicinal cannabis.

  • Medicinal cannabis products for the treatment of GI disorders are not listed on the Pharmaceutical Benefits Scheme (PBS) and patients must meet the annual treatment costs.36

  • Start cannabis products at the lowest possible dose and increase slowly over days or weeks to determine if the treatment is effective.

  • Do not drive when taking medicinal cannabis products containing THC.36

  • If you are new to cannabis, or if you are sensitive to the side effects, try a low-THC cannabis product or one with a high CBD to THC ratio.31

What Are the Next Steps? In most states in Australia, most GPs and specialists can prescribe CBD oil. However, they will need to apply under the special access scheme. If your doctor is unwilling to apply on your behalf or uncomfortable prescribing medical cannabis, they can refer you to our clinic. We do virtual consultations nationwide and in-person at our flagship clinic in Sydney. Click here for a quick online eligibility test to see if you qualify. You can also mail us at and we can advise if medical cannabis could be an option for your condition. More information

  • Australian Centre for Cannabinoid Clinical and Research Excellence

  • Centre for Medicinal Cannabis Research and Innovation

  • Therapeutic Goods Administration (TGA) guidance for the use of medicinal cannabis in Australia patient information

  • Gastroenterological Society of Australia


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