Medical Cannabis

What is cannabis?

If you’re wondering whether cannabis can help alleviate symptoms of inflammatory bowel disease, you’re not alone. Many individuals living with Crohn’s and colitis are interested in learning more about cannabis as an emerging treatment.

Patients are strongly encouraged to speak with their health care provider and use caution if/when experimenting with cannabis.

The cannabis plant is said to be one of the oldest agricultural crops. One strain of the plant, called hemp, has been used for industrial purposes to make food (hemp seeds), paper, clothing, rope, insulation, biofuel and more over the ages. Other strains of cannabis, bred to have leaves and flowers, are higher in “cannabinoids” and can be used for medical and recreational purposes. 

Using cannabis as a medicine dates back to the ancient world, where it was used to heal wounds and soothe pain. Recently, the medical potential of cannabis has been gaining interest for its effects on different symptoms. Medical cannabis became legal in Canada in 2001 to treat a number of conditions.

Cannabis has also been used recreationally for its psychoactive properties. In October 2018, Canada passed Bill C-45 (the Cannabis Act) which legalized recreational cannabis across the country. 

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Medical vs recreational

There is no real difference between medical and recreational cannabis. It is the intent that is different, but the drug is the same. “Medical” or “recreational” refers to the purpose people are using it for. Sometimes there is an overlap. 

If you intend to use cannabis for its medicinal properties, you may look for features of the plant that make you feel better and give your body relief. Typically, medical cannabis contains a higher concentration of CBD.

If you are using cannabis for recreational purposes, you may be concerned with the amount of THC in the plant and focus on the method of consumption and the timing of consumption to suit your activities. Remember, THC is what gives people that euphoric “high” effect.

Medical cannabis is prescribed by a healthcare provider. The patient would get a medical authorization to purchase from a licensed seller.  More about accessing cannabis is explained later in this section under How to Access Cannabis. 

The legalization of cannabis may increase opportunities for clinical research on the role of cannabis in the management of inflammatory bowel disease. 


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Why choose cannabis?

People with inflammatory bowel disease may be considering using cannabis for a variety of reasons.

  • There is a desire for an alternative or complementary treatment to existing traditional therapies.

  • There is a perception of cannabis as natural and harmless.

  • Cannabis use is growing in popularity and less “taboo”.

  • There is a possible benefit as an alternative to opioids and other drugs.

Many people living with IBD have reported relief of symptoms like pain, nausea, diarrhea, low appetite, and an improvement in overall mood when using cannabis.

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Ways to consume cannabis

Cannabis products are available in many different forms. Cannabis can be smoked, inhaled, ingested or made into oils, capsules, and edibles. Most people using cannabis for medicinal purposes consume it as an oil or vapor. The method of consumption can influence the effects of cannabis, which is explained in more detail below under The Effects of Cannabis.


Traditionally, cannabis has been smoked as a joint. Smoking carries with it many of the risks of smoking tobacco, so health professionals have advised against smoking cannabis. Cannabis smoke is filled with many of the same chemicals as tobacco and can be harmful to the lungs.

Vapourization (vape)

Vaporization has become a popular way to consume cannabis, both medically and recreationally.  Vaping involves heating cannabis into a vapour and inhaling it through a mouthpiece. 

Oil and edibles

Edibles such as a brownie or gummy bear can also be consumed, though these are only legal in some provinces across Canada. Edibles are more risky for a number of reasons. If the ingredients are not measured correctly, homemade edibles can more potent than anticipated.

In addition, when cannabis is swallowed, the effects take longer to onset. This can cause people to consume more cannabis than needed to get the desired effects and can lead to an overdose. Ingested cannabis also takes longer to clear from the body.

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Cannabinoids and strains

Cannabinoids (THC vs CBD)

Cannabis contains a variety of compounds called cannabinoids which are the active ingredients in the plant (there are over 70 cannabinoids reported so far). Two of the most dominant cannabinoids are Delta-9-tetrahydrocannabinol (THC) and Cannabidiol (CBD). 

THC may be the most recognized cannabinoid. It is associated with the psychoactive ingredient in cannabis that gives users the “high” or euphoric feeling. It is also associated with some negative effects such as anxiety and irritability. 

CBD is associated with cannabis’ more calming effects. It may also counter some of the negative symptoms associated with THC.

The endocannabinoid system

The human body has an Endocannabinoid System (ECS) which regulates different functions such as pain, appetite, mood, and stress response. The ECS is comprised of endocannabinoids (natural cannabinoids produced by our bodies) that stimulate our cannabinoid receptors.

Receptors detect changes in the body’s environment. They are found in different parts of the body including the brain, liver, nervous system, and especially, the gastrointestinal tract. 

When people consume cannabis, the cannabinoids (THC, CBD and others) mimic those found in the body and activate the same receptors. In the gut, these receptors trigger certain responses such as regulating inflammation, pain, nausea, satiety, vomiting, and possibly, altering gut barrier function (the leakiness of the gut).

To take effect, the cannabinoids bind to endocannabinoid receptors on the surface of different cells. Once locked in, some of the effects that can take place have been reported to improve symptoms in patients with inflammatory bowel disease.

Strains of cannabis (Sativa vs Indica)

Different strains of cannabis have different combinations of cannabinoids. CBD and THC are the major active ingredients in the cannabis plant, but when cannabis is consumed, users get the effect of a number of products in the plant.

The two most common strains of cannabis are called indica and sativa. Indica is said to have a more relaxing effect while sativa has a more energizing effect. There are also hybrid strains that combine both.

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Effects and safety of cannabis

How long will the effects last? 

Different methods of consumption will alter how long the effects of cannabis will last. It’s important to bear this in mind when considering how to consume cannabis for medicinal purposes. 

Intensity (how strong the effects are) is highest with inhalation (smoking or vaporizing) but the duration is shorter. If you smoke or vaporize cannabis, the effects are very rapid and can usually be felt within a few minutes, usually peaking within 30 minutes to an hour. Effects can last between two and four hours.

If you ingest cannabis orally with a product like a brownie or oil, the effects are much slower to onset and usually don’t reach their peak until two or three hours later, and last much longer. Caution should be used with ingesting cannabis since it takes longer to enter the bloodstream, longer to “feel” the effects, and longer for the effects to subdue. Note that edible cannabis products are only legal and available in some Canadian provinces.

Short-term side effects

Cannabis is relatively harmless in low to moderate amounts. But using cannabis can cause some short-term side effects including: 

  • Physical impairments such as short-term memory or concentration loss, dizziness, drowsiness, fatigue, headache, disorientation, confusion, and feeling faint

  • Impaired motor skills and perception

  • Increased anxiety, paranoia, suspiciousness, hallucinations

  • Dry mouth and coughing

  • Skin reactions

  • Nausea, vomiting

  • Fast heartbeat

Adverse effects of long-term cannabis

There is little data available on the long-term dangers of cannabis use so we advise to use caution.

  • Impact on brain functions like memory, concentration, decision-making, and judgement 

  • Increased risk of mental health problems such as the development of depression, anxiety, psychosis, and schizophrenia

  • Physical problems that can affect the respiratory system like symptoms of chronic bronchitis when smoking

  • Potential risk of dependency or addiction.  A small percentage of cannabis users develop a dependence, which is much lower than other substance use such as alcohol, tobacco, and other drugs.

  • Can lead to withdrawal symptoms if stopped, such as anger, aggression, nightmares, insomnia, headaches, anxiety, irritability, depression, cravings, decreased appetite, stomach pain, chills, and sweating 

  • Unlike most other drugs, there have been no deaths attributed to cannabis alone. (Someone would have to consume an impossibly high amount of cannabis in order to overdose).

  • Smoked cannabis may be detrimental in Crohn’s disease. A limited number of studies have reported improvement with smoked cannabis.

  • Heavy cannabis use is associated with more severe GI disease, but it is relatively harmless in low to moderate amounts.

Cannabis Hyperemesis Syndrome

Heavy cannabis use is associated with cannabis hyperemesis syndrome, a condition involving nausea, low appetite, vomiting and abdominal pain. Symptoms resolve when people stop using cannabis. 

Increased risk of surgery

In patients with Crohn’s disease, using cannabis for 6 months or more was a strong predictor of requiring surgery, according to this study.

Cannabis and young people (teens)

It is advised that those under 21 years old do not use cannabis since their brain is not fully developed. Cannabis use can impact brain development, specifically the pre-frontal cortex, which is the area of the brain that is last to develop. This area is responsible for skills like thinking ahead and weighing risks and harms about decisions we make. Certain mental health issues are also at an increased risk with cannabis consumption during this time.

Fertility and pregnancy 

There are some suggestions that long term cannabis use may affect sperm quality by decreasing the sperm count, concentration and motility. Early research suggests cannabis may delay or inhibit ovulation and lower sperm counts but is based on self-reported use. On the other hand, a recent study suggests cannabis may not interfere with trying to conceive. Until more research has been done, doctors say it’s better to steer clear.

Cannabis use during pregnancy can negatively impact the behavioural and cognitive development of the baby including resulting in low birth weight, preterm labour, and stillbirth. The Society of Obstetricians and Gynecologists of Canada recommends to avoid cannabis during pregnancy. 

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Cannabis for IBD management

Can cannabis improve the quality of life for people suffering from gastrointestinal disorders? Research is in its early stages, but patients have reported some therapeutic effects in the management of abdominal pain, nausea, diarrhea, and improvements in sleep, appetite and quality of life. 

Observational versus clinical studies

Since cannabis hasn’t been legal for long, research is limited. Health professionals aren’t completely aware of the therapeutic role cannabis can play but can draw from some clinical and observational studies. They also haven’t had a chance to study long term effects since cannabis’ growing popularity in medicine is recent.

Observational studies suggest patients use cannabis to relieve symptoms associated with IBD. In observational studies, the investigator simply observes participants and records what happens without intervening. Clinical studies, on the other hand, are controlled and randomized to achieve unbiased results. This type of research aims to answer a specific question.

There are some flaws in human studies that examine cannabis and the management of IBD including:

  • Cannabis use is often underreported.

  • Recall bias is present. Recall bias is an error caused by people’s recollections or memory not always being accurate.

  • There are no objective parameters or measurements to show symptom improvements.

  • Small sample sizes, short research timeframes, and little or no follow up can affect results.

Symptom relief and quality of life

Observational studies in patients with IBD are still limited, but early research suggests patients use cannabis to relieve symptoms associated with IBD.

The number one reason patients use cannabis is to control abdominal pain. Patients with IBD also reported improvements in joint pain, abdominal pain and cramping after using cannabis. Improvements in sleep, reduced diarrhea, nausea and appetite were also reported after using cannabis.

Best strain for symptom relief 

It is not yet known what the best type or strain of cannabis is for symptom management in IBD. There are some suggestions that the indica strain is more effective at reducing pain, controlling nausea, and helping with sleep but there is little evidence on the different benefits of different strains.

Cannabis and gut inflammation  

Cannabis may mask inflammation because the symptoms have improved, but there is little evidence to support that cannabis plays an anti-inflammatory role. There is no evidence that cannabis positively alters the disease course. 

There is also no evidence to demonstrate any benefit of cannabis in gut motility disorders. Gut motility is related to the movement of the digestive system. It is the expansion and contraction of the muscles in the GI tract.

Heavy cannabis use is associated with more severe GI disease, but it is relatively harmless in low to moderate amounts. The use of cannabis for more than 6 months has been associated with an increased risk for surgery in patients with Crohn’s disease. Also smoked cannabis may be detrimental in Crohn’s disease, and a limited number of studies reported improvement with smoked cannabis. 

There is little evidence to support the use of cannabis for treatment in GI disease but some suggestion that it improves quality of life and relieve some symptoms.

Cannabis and other medications 

Cannabis cannot replace conventional treatment or medications used for Crohn’s or colitis. There is no evidence that cannabis is an effective anti-inflammatory so you don’t want to stop first line therapies recommended by your physician and replace it with cannabis. 

Cannabis cannot cure IBD. If you are using cannabis in combination with other medications, discuss this directly with your health care provider. 

Research into cannabis and IBD

To find out more about research studies that investigates the effectiveness of cannabis for IBD management, click on the articles below: 

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Dosing for medical cannabis

Dosing for medical cannabis is highly individualized. There are no defined doses of cannabis for specific medical conditions, though current information suggests up to 3 grams daily is common for experienced users.  

Research has concluded that a combination of THC and CBD is most effective. When used individually, THC was more effective. 

If you have never used cannabis before, do so with someone you trust close by in case you experience adverse effects. Start slow and gradual (for example 1 mg of THC) and wait 30 minutes before taking more puffs or inhalations to gauge the strength and effects taking place.

Increasing your dose should be done slowly and as needed. There is not a lot of data on the best dose or optimal timing. Start with a low amount of cannabis with a small quantity of active ingredients (especially low amounts of THC to avoid major psychiatric effects).

Remember to keep your health care providers informed of your dosing patterns.

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Talking with others about cannabis

Talking with health care providers

Since cannabis has no effect on inflammation, it does not replace conventional medical therapy.  Be open and upfront with your healthcare provider.

Let them know what you’re using and why in case there are any drug interactions with another prescription medication to be aware of. It also helpful to log or note your dosing and symptoms and report this information to the health care provider. 

Come prepared to answer these questions: 
  • Which symptoms does cannabis help you manage?

  • How much are you consuming (in grams, if possible)?

  • How are you consuming it (smoking, vaping, oil, etc.)?

  • What type of strain are you using? 

  • What has your experience been like?

Talking with family and kids

When discussing your cannabis use with family, be prepared to answer questions honestly and keep the conversation open and ongoing. Explain the benefits of cannabis for managing your symptoms and explain that you are consulting with your healthcare provider throughout the process.

With children, you may want to gauge how much they know about cannabis and how they feel about it. Explain the facts, focusing on medical benefits, physical side effects, safety, legal implications (like cannabis and driving) and any risks to be aware of.

Remember to reflect on your substance use and coping strategies so you can better address these conversations with your children. Build trust so they are able to come to you with questions and encourage them to share their own experiences. 

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Cannabis and the law

The Cannabis Act 

Medical cannabis became legal in Canada in 2001. Recreational cannabis, on the other hand, recently became legal in October 2018 under the Cannabis Act. The Act helps set rules around production, distribution, sale and possession of cannabis.

It outlines safety and quality requirements, including restricting access to youth and specifying criminal penalties for those who break the law. Cannabis is legal for adults 18 or 19 years old, depending on the province or territory.  

Here are some important things to note under this Act:

  • It is legal to possess up to 30 grams of cannabis at a time.

  • It is legal to consume in authorized locations only. Authorized locations differ between provinces and territories. As a general rule, smoking in your home is okay (if you rent, check with your landlord). Smoking in most public greenspaces is okay. Don’t smoke close to recreational facilities, schools, or hospitals.

  • It is legal to grow up to four cannabis plants per household for personal use.

  • There are criminal penalties for offences such as driving impaired or crossing international borders with cannabis.

  • Legal cannabis includes fresh or dried cannabis, cannabis oil, and seeds and plants.

  • Edible cannabis products and cannabis extracts are still illegal to purchase in some provinces, though you can make your own. 

Cannabis and driving 

The side effects of cannabis use can impair driving. Driving while impaired by drugs including cannabis is illegal. Law enforcement are trained to detect drug-impaired drivers.  Repercussions of driving impaired can include fines, confiscations and charges. Talk with your health care provider about the timing of your cannabis use to ensure safety on the road. 

Rules regarding driving with cannabis differ between provinces. Here are some general recommendations:

  • Keep receipts to show cannabis was purchased at an authorized outlet.

  • Keep cannabis in its original, sealed packages.

  • Travel with cannabis in the trunk, out of reach.

  • Don’t leave cannabis unattended in the car. Transport it from point A to point B.

Travelling with cannabis

Do not cross international borders with cannabis - no exceptions. It is illegal to travel outside of Canada with cannabis, even to and from countries where cannabis is legal. In rare circumstances, Health Canada may authorize a person to bring cannabis across international borders for medical purposes. Learn more about cannabis and international travel. 

Flying with cannabis within Canada is legal. Be prepared to show medical documentation in accordance with regulations if the amount you’re carrying exceeds the possession limit for recreational personal use (30 grams). Carrying cannabis oil in a carry-on luggage must follow the liquid restriction of 100 ml or less. 

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Workplace and school

Cannabis use in the workplace 

Under the Canadian Human Rights Act, employers are obligated to accommodate those with medical cannabis authorizations, to the point of undue hardship. Medical cannabis must be treated like any other prescription medication. However, the Non-Smokers’ Health Act does prevent smoking and vaping of cannabis in the workplace. 

Employers can develop policies related to hazards from impairment in the workplace to ensure impairment doesn’t impact safety.  Understand your employer’s policies regarding medical cannabis prior to using it at work. To learn more about cannabis in Canadian workplaces, click here.

Cannabis in post-secondary school 

Although now legal, consuming cannabis is prohibited at schools, on school grounds, in public areas within 20 metres of these grounds, and in child care centres including home care, in accordance with the Smoke-Free Ontario Act. This Act also applies to tobacco and electronic cigarettes. 

Those who require cannabis for medical purposes are permitted to carry it on school property. Students and staff can use medical cannabis on school property in non-smoking and non-vaping form (for example, cannabis oils and capsules). School boards are responsible for developing policies pertaining to the administration and storage of medications in schools. 

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How to access cannabis

Recreational and medical cannabis 

Cannabis can be purchased directly from a federally licensed seller or authorized provincial outlet, or you may grow your own. 

If you would like to access cannabis for medical use, speak with your health care provider to discuss if cannabis is right for you. They can provide you with a medical authorization in compliance with the Access to Cannabis for Medical Purposes Regulations (ACMPR)

With this document, you can register with a licensed producer of your choice by contacting them directly or visiting their website to fill out a registration form. You can also register to purchase the materials to produce your own cannabis or have another person produce it on your behalf. 

Personal storage limits under the Cannabis Act indicate you are allowed to possess either a) a 30-day supply of what your healthcare provider has prescribed or b) 150 grams -- whichever comes first. Be prepared to show law enforcement, if requested, that you are authorized to carry more than the 30 grams of cannabis for recreational use. 

You can switch licensed producers at any time by cancelling your registration with your current producer and obtaining another medical document from your healthcare provider to register with your new producer.

Legal cannabis products will have an “excise stamp” on the package which indicates duty has been paid as well specific identifiers and security features. The packaging would also include the standardized cannabis symbol and mandatory health warnings. 

Insurance Coverage 

There is currently no public insurance coverage for medical cannabis. Since medical cannabis does not yet have a drug identification number (DIN), provincial health insurance programs, such as OHIP in Ontario, do not cover it. It is not included on the drug formularies and did not go through the formal Health Canada process to become an approved drug.

Your workplace benefits plan may cover medical cannabis for certain health conditions through a private insurance plan. Health spending accounts typically consider medical cannabis as an eligible expense. Contact your Human Resources department to find out if your workplace benefits covers medical cannabis.

Compassionate care

Many licensed producers offer “compassionate pricing” or discounts to people on social assistance or who are considered low-income.

Veterans Affairs Canada has a reimbursement policy for medical cannabis purchased from a licensed producer, up to three grams per day. 

Tax Credits

Under Canada’s Medical Expense Tax Credit, cannabis is an eligible medical expense that you can claim on your tax return. To do this, you’ll need receipts from an approved Health Canada-licensed producer and your medical authorization (prescription) from your doctor. 

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Video: Cannabis Use for IBD Symptom Management

Watch the video below to learn from a gastroenterologist about cannabis use to manage symptoms of Crohn's and colitis.

Speaker: Dr. Christine Turbide is a gastroenterologist from the Foothills Medical Centre and the University of Calgary.

Video: Cannabis and Inflammatory Bowel Disease 

Watch the video below to learn more from a gastroenterologist and expert about cannabinoids and the effects of cannabis on the mind and body.


Dr. Keith Sharkey (Ph.D) is a Professor of Physiology and Pharmacology and Crohn's and Colitis Canada (CCC) Chair in IBD Research at the University of Calgary.

Dr. Yasmin Nasser (MD Ph.D. FRCPC) is a is a Clinical Assistant Professor in the Department of Medicine and a clinician-scientist in the Division of Gastroenterology and Hepatology at the University of Calgary.

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