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Can Cannabis Help IBS?
6 min
Elian Rosenfeld, PhD by Elian Rosenfeld, PhD


In recent years, there has been a growing interest in the use of cannabis for a number of chronic conditions, such as Irritable Bowel Syndrome (IBS). The underlying causes of IBS are poorly understood, and available medications are limited and often carry burdensome side effects. As a result, alternative therapies like medical cannabis may be an appealing means of treatment for IBS sufferers. 



The Endocannabinoid System

In recent years more and more research has illuminated the manner in which cannabis affects the body. Cannabis is made up of hundreds of compounds, including cannabinoids like THC and CBD. THC can cause psychotropic effects that include feelings of intoxication or mild euphoria while CBD does not have such effects.

In the 1990s, researchers found that cannabinoids are also naturally present in the human body, in what is known as the endocannabinoid system (ECS). Subsequent research found that the ECS has a vital role in maintaining equilibrium for the central nervous system and the immune system, and the regulation of visceral pain. 

The ECS also plays a large role in creating homeostasis in the digestive system, and is involved in the internal biological processes that lead to nausea, vomiting, gut motility, and intestinal inflammation. As a result, the ECS may be an important therapeutic target in the treatment of diseases affecting the gastrointestinal tract.

The gastrointestinal tract has two primary cannabinoid receptors, known as CB1 and CB2—both are present in the gastrointestinal tract. THC helps activate both CB1 and CB2 receptors, and some research indicates that activating cannabinoid receptors in the gastrointestinal tract may reduce in motility and inflammation. In addition, animal studies have found that that activation of CB1 receptors inhibits visceral pain—pain in internal organs.

Medical Cannabis Treatment for IBS

There is very limited research on medical cannabis and IBS. Given the legal status of cannabis in the past, this may be understandable and does not necessarily mean it isn’t a promising therapy. Several survey studies have found that patients with IBS who used cannabis do experience symptom relief, although not all studies have come to the same conclusion. 

  • A study was conducted on the impact of dronabinol (a synthetic THC) on visceral sensitivity to rectal distension. This randomized, double blind study was conducted with 10 IBS patients and 12 healthy volunteers. The study found that dronabinol does not affect visceral perception to rectal distension or alter the threshold of discomfort. 
  • A pharmacogenetic trial examined the impact of dronabinol on colonic motility and sensation in individuals with IBS and the genetic variants in IBS subtypes. The study included 35 patients with diarrhea predominant IBS, 35 patients with constipation predominant IBS, and five patients with alternating IBS. The study found that 5 mg of dronabinol reduced fasting colonic motility in patients with diarrhea predominant and alternating IBS and that specific genotypes may play a role on the effects of the medication. 
  • A small, short-term randomized control trial with 36 participants aged 18 to 69 with diarrhea predominant IBS evaluated the effect dronabinol had on gastrointestinal transit. Patients were randomized to dronabinol 2.5 mg twice daily, dronabinol 5 mg twice daily, or a placebo for two days; no treatment effects were found. 

In addition, there is a theory that holds that depressed endocannabinoid levels correlate with several difficult-to-treat conditions, including fibromyalgia, IBS, and migraine. The theory is predominantly based on pre-clinical research, and is as such still in preliminary stages. If the theory is proven, however, it would contribute to understanding why cannabis is effective in treating these conditions.

Side Effects of Cannabis 

In the studies on dronabinol, common side effects included fatigue, drowsiness, and headaches. In general, CBD is a well tolerated drug with very few side effects. Some of the short-term side effects of THC can include memory, motor and judgement impairment and the long term effects can include cognitive impairment, a small risk of addiction, as well as an increased risk of developing a psychotic disorder. Further research is necessary to explore the potential interaction between other IBS medications and specific doses and forms of CBD and THC.


Legal Use

Currently, medical cannabis for the treatment of IBS is not explicitly endorsed by any country. States such as the Netherlands and Germany allow doctors to prescribe medical cannabis for any condition if standard treatment is not effective for their patient. In Israel, a doctor can provide “exceptional approval” for a patient to use cannabis if their medical condition is not on the list of specified conditions but their condition is deemed exceptional.

In the United States, there is state-by-state variation in the legal status of medical cannabis. The District of Columbia and 33 states (Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Illinois, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, Washington, West Virginia, Utah, and Vermont) allow the use of medical cannabis. None of these states explicitly list IBS as qualifying medical condition for cannabis use. However, nausea or chronic pain are qualifying medical conditions in most of these states and in some of these states other debilitating conditions can be determined eligible at the discretion of a physician. These conditions and qualifications would likely make many IBS patients eligible for medical cannabis use. 


While some patients report that medical cannabis provides relief from their IBS symptoms, there is not enough high quality research or evidence to determine if medical cannabis is an effective treatment for IBS and its symptoms. More research, especially randomized clinical trials, is needed to assess the effect of medical cannabis on IBS. 

About IBS


Irritable Bowel Syndrome, or IBS, is a relatively common disorder that affects the intestines. It can cause a great deal of discomfort and even disability in sufferers, with many people getting inadequate relief. IBS is the most common type of gastro-intestinal disorder, occurring in 10-15% of adults. It can affect men and women, both adults and children, although women are twice as likely to develop IBS than men.

Sufferers often see many doctors seeking relief. They often have many procedures performed and undergo extensive testing, with no specific abnormality found. This can be extremely frustrating for patients and their families, who do not get an explanation of why they are suffering from chronic pain and discomfort. 


The main symptoms of IBS are:

  • Cramps or pain in the stomach and abdomen. Usually these feel worse just after eating, and feel better after a bowel movement. 
  • A bloated stomach that feels uncomfortably swollen.
  • Gaseousness.
  • Diarrhea or constipation, meaning a sudden need to relieve oneself urgently, and sometimes having real difficulty having a bowel movement. It’s quite common to experience both, at different times. 

Some other symptoms of IBS that one might experience:

  • Uncontrollable flatulence (farting)
  • Backache 
  • Passing mucus in the stool, or when trying to have a bowel movement
  • Having trouble peeing, needing to pee often, or feeling sudden urges to pee
  • Incontinence, ie. not always able to control when you have to relieve yourself
  • General tiredness and feeling low on energy
  • Feeling nauseous

Most people with IBS find that there are times when their symptoms are worse, and times when they feel less severe. Triggers which cause symptoms to flare up and get worse can include: 

  • Food. People with IBS often find that some foods, like milk and dairy products, acidic fruits like citrus fruits, beans, cabbage, wheat, and carbonated soft drinks make their symptoms worse. It’s not the same as a full food allergy or intolerance, though.
  • Stress. It’s very common for symptoms to get worse during times of stress.
  • Hormones. Women find that their symptoms get worse at certain points in their menstrual cycle.

When to see a doctor

If you experience any of the symptoms of IBS, together with any of the following symptoms, you should see a doctor urgently. It could be a sign of a more serious illness.

  • Weight loss
  • Bleeding from the rectum
  • Difficulty swallowing
  • Vomiting that doesn’t have an obvious cause
  • Night-time diarrhea
  • Persistent pain in the gut that doesn’t get any better after a bowel movement

Even if you don’t have the above symptoms, it is important to rule out other potential conditions so seeing a doctor is important and the first step in getting relief.


There’s no single test to diagnose IBS. Along with performing a physical exam, your doctor will ask you about your symptoms, and carry out certain tests to rule out other causes like celiac disease, intolerance to gluten or other food types, a bacterial infection, or parasites. 

You can expect to answer plenty of questions about your medical history and your symptoms, including how often you feel symptoms of IBS and when they feel more severe. 

Some of the tests that you might undergo include:

  • X-ray or CT scan, to check for growths or obstructions in the abdomen, pelvis, and intestine.
  • Lactose intolerance tests, to see if the body is producing the enzyme lactase that is needed to digest dairy products. 
  • Breath tests, to check for too much bacteria growing in your small intestine.
  • Stool tests, to check for bacteria or parasites in the stool, or for a digestive enzyme called bile acid that’s produced in the liver. 
  • An upper endoscopy, to inspect the upper part of the digestive system and take a tissue sample from the small intestine. It’s used to check for excessive bacteria growth.
  • Flexible sigmoidoscopy or a colonoscopy, to inspect the lower part or entire length of the colon.

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