Cannabis is a genus of plant that contains three varieties: Cannabis indica, Cannabis sativa, and Cannabis ruderalis. It is a flowering herb with a long, rich history of medicinal, recreational, nutritional, and industrial use throughout the world. Recently, there has been a surge of attention cannabis, and people are interested in seeing the plant legalized for medicinal and recreational purposes. Many people are excited about the possibility of increased research on the medicinal uses and safety of cannabis, which legalization would make more accessible.

Cannabis Animation Video

Cannabis Presentation Video

History of Cannabis

The cannabis plant originated in central Asia, where people first discovered it at least 12,000 years ago, during the early days of agriculture. Initially, they would use cannabis by eating the nutritious seeds and creating rope and textiles from the hemp stalks. However, the first written record of medical cannabis use in China was nearly 5,000 years ago.

Over the years, cannabis use spread across the continent and then the world, and many peoples continued to use it to treat a variety of ailments. Ancient Egyptians used cannabis to treat hemorrhoids and ease childbirth. Evidence from India shows documents dating back thousands of years praising its ability to easy anxiety and increase happiness. There is evidence in many parts of the world of medicinal use of cannabis, but even more evidence of industrial use, with importance placed on hemp textiles.

A book published in Medieval England known as the Old English Herbarium included several uses for cannabis, such as a poultice made of pounded hemp to dress wounds, a liquid hemp concoction used to ease ‘pain of the innards’, and a cannabis and fat mixture applied to the breast to ease soreness in women who had just given birth.

Throughout the 19th century, it was a popular remedy in the United States. Consumers could purchase cannabis tinctures and other preparations from pharmacies, and use these products to treat a range of ailments. These included gastrointestinal diseases, mental illnesses, nausea, headaches, insomnia, asthma, epilepsy, menstrual cramps, and many other symptoms, diseases, and disorders.1

However, by the 20th century, cannabis began to fall out of favour in North America. In 1923, Canada was one of the first countries to add cannabis to its list of prohibited drugs, leading to a 95-year prohibition on cannabis, ending upon legalization in October 2018.

Throughout the mid 20th century, researchers found and isolated a variety of cannabinoids, allowing them to understand more about the function of cannabis. However, it wasn’t until 1988, when they discovered a unique receptor in the human body that responded to cannabis, which is part of what we now call the endocannabinoid system, that they truly began to understand the unique nature of cannabis. Subsequent research on this receptor led to the 1992 discovery of anandamide, a neurotransmitter that activated some of the same receptors as cannabis. In 1993, researchers discovered another receptor in the endocannabinoid system, as well as more of these unique neurotransmitters.

In 2001, Canada introduced the Medical Marijuana Access Regulations, allowing individuals with certain diseases to access government-issued cannabis if their physician recommended it and they met established criteria. In 2003 and 2004, two separate bills were introduced by the federal government with the goal of decriminalizing small amounts of cannabis, but neither of these succeeded.

While public opinion of cannabis has gone through many shifts, in recent years, public interest in Canada has continued to grow. With legalization of cannabis in Canada as of 2018, it is hopeful that we will see more research, dialogue, and deeper understanding of how cannabis works to help people.

Cannabinoids and the Endocannabinoid System2

Cannabis is composed of many different substances, and more than 100 of these are what we call cannabinoids; these, possibly along with other compounds known as terpenes, are responsible for the effects of cannabis. Cannabinoids most likely work by interacting with a complex system in the body called the endocannabinoid system (ECS). Our bodies naturally produce a family of neurotransmitters called endocannabinoids, which interact with receptors located in the brain, muscles, fat, and digestive tract. These receptors are called cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2).

Scientists only recently found evidence of the ECS when they discovered CB1 in 1988, so research is still ongoing into exactly how it functions. However, most data find that it helps our bodies regulate pain, mood, appetite, gastrointestinal motility, memory, emotions, stress response, immune function, and more. When a person ingests the plant-based cannabinoids in cannabis, which are similar molecular shapes to endocannabinoids, they fit into the CB1 and CB2 receptors and trigger reactions that result in either very high or very low levels of specific neurotransmitters, which the cells of the nervous system, as well as other systems in the body, use to communicate with each other.

The ECS is very important when it comes to medicinal cannabis, because changes in how the ECS functions might have an important relationship to the pathology of chronic conditions and could be tied to the efficacy of cannabinoids.

The two most important cannabinoids, and the two that typically compose the majority of cannabinoids in cannabis, are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).

THC, the most recognized cannabinoid, is associated with reduced nausea and pain, increased appetite (the munchies), and psychological effects such as relaxation, euphoria, and altered sensory perception, which are responsible for making users feel ‘high’ or intoxicated. THC is also the primary source of the negative psychological effects associated with cannabis use, such as irritability, anxiousness, and paranoia.

CBD does not seem to produce intoxicating effects (non-psychotropic) but it is responsible for some of the plant’s sedative effects. CBD can help reduce convulsions, nausea, and inflammation. It might also lessen some of the negative symptoms associated with THC, especially anxiety and paranoia.

One Plant, Many Uses

When we develop cannabis to grow tall and strong with thick fibrous stalks that are low in THC we typically refer to it as hemp; people mostly use hemp seeds for food and its fibres for industrial purposes, such as for creating textiles and building materials, or for extracting CBD for medicine. When we breed it to have lush leaves and flowers that are high in cannabinoids, we use the flower buds for medicinal or recreational purposes. Some people refer to cannabis used this way as marijuana.

Typically, Cannabis ruderalis is very low in cannabinoids, and only used for hemp. Cannabis indica and Cannabis sativa can be grown for either industrial or medicinal/recreational uses, depending on how the plant is cultivated. Plant breeders have created innumerable different strains of cannabis, each of which has a different combination of cannabinoids, with variable potency results. Successful medical use of cannabis involves finding an ideal strain, representing different ratios of THC and CBD, for each patient’s needs.

Medicinal Uses of Cannabis

The list of conditions that cannabis is purported to treat or cure is very long, and continues to grow, but the research is still lacking in many areas. This is largely due to cannabis being both stigmatized and illegal in most parts of the world for the past century, so research might increase as legalization becomes more commonplace. It is also difficult for researchers to conduct double-blind studies for most cannabis products because subjects might be able to determine whether they are on the active therapy or placebo.

However, current research indicates that some conditions may be clinically improved by cannabis use. These include inflammatory bowel disease,3 multiple sclerosis,4 neuropathic pain,5 nausea and vomiting caused by cancer or chemotherapy,6 pediatric seizure disorders,7 and a wide variety of other illnesses. Here, we will focus on gastrointestinal symptoms and conditions that might be ameliorated by cannabis.

Cannabis and IBD

Some research suggests that the ECS might play a role in gut health. Particularly, inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, might be influenced in part by alterations in the ECS, as this system might modulate inflammatory responses.3 In addition, research shows that levels of anandamide, an endocannabinoid, are much lower in the inflamed gut mucosa of those with IBD than in healthy gut tissue.3 Early research on the effects of cannabis on IBD is quite promising, but we still have far to go before we can definitively say that cannabis is an effective treatment for IBD.

One retrospective study in Israel asked 30 patients with Crohn’s disease about their disease severity before and after using cannabis and found great improvements.8 They found that 70% of the patients experienced a decrease in Crohn’s disease symptom severity when using cannabis, and that many were able to reduce or eliminate the medications that they were using. For example, before using cannabis, each individual took some sort of prescription medication to treat their disease. When using cannabis, nine individuals were able to cease all prescription medication use. They also reported a drop in daily bowel movements from eight to five per person, as well as a slight decrease in the number of surgeries required.

Since this was a retrospective study, meaning it relied primarily on patient memory and subjective symptoms, the study isn’t as strong as a double-blind study would be. However, the changes in more objective measurements (such as surgery and prescription medication records) point to the possibility that cannabis was quite beneficial for these individuals. It should be noted that individual responses can vary. You should discuss your specific situation with your physician and pharmacist prior to stopping any medication you take for a chronic condition.

One prospective study provided 13 IBD patients (11 with Crohn’s disease, 2 with ulcerative colitis) who were not using cannabis with 50 g of cannabis to smoke as needed to relieve symptoms over the course of three months.9 After this time, all the patients had smoked the full 50 g, and they saw improvements in their health. The Crohn’s disease group’s Harvey-Bradshaw index scores (an index that rates Crohn’s disease symptoms) dropped from an average of 11.36 to 2.68 (great result), with the largest improvements in general wellbeing and abdominal pain. The subjects experienced significant improvement in pain, health perception, depression, social functioning, and ability to work. They also had an average weight gain of 4.3 kg over the three months (a health improvement), and a reduction in average number of daily liquid stools from 5.54 to 3.18.

These researchers support the idea that the benefits were the result of cannabinoids having anti-inflammatory, anti-motility, and analgesic effects. With only 13 participants, this study is too small to come to generalizations about most people, but it does show that cannabis might be effective for some individuals with IBD. The fact that the subjects knew they were taking the therapy may also have had an impact on their perception of improvement.

At this point, much research shows a possible benefit for individuals with IBD taking cannabis, but we still don’t know quite how it works. It might be limited only to pain relief and increased appetite, but it might also help by reducing inflammation. We need more research on the topic before we can know for sure how cannabis affects IBD.

Cannabis and Other GI Symptoms

While most research on cannabis and the gastrointestinal tract focuses on IBD, it might be helpful for individuals with other digestive illnesses. For instance, it seems to universally be effective at reducing abdominal pain.10 It can be especially useful for individuals taking opioid medications for abdominal pain, as research shows that cannabis helps patients cut down on or eliminate their need for opioids and provides a treatment with fewer side effects.11 Cannabis also helps individuals who have a difficult time eating enough by increasing appetite and it can help reduce diarrhea and nausea.12 There is quite a bit of evidence for many of these symptoms, so if you think cannabis might be useful for you, please consult your health care team to discuss the benefits and risks associated with its use.

One other gastrointestinal finding is that cannabis users are less likely to have non-alcoholic fatty liver disease than those who don’t consume cannabis, possibly due to metabolic benefits from cannabinoids.13

Negative Effects of Cannabis

While cannabis seems to provide many benefits, it does have its drawbacks and side effects.14 Short-term side effects (those that only affect you while the cannabinoids are in your body at higher levels) can include short-term memory impairment, diminished motor skills, decreased reaction times, fatigue, anxiety, panic, increased heart rate, increased or decreased blood pressure, and dry mouth. These effects can make activities such as driving and operating large machinery dangerous, so avoid cannabis before any activity that requires quick thinking and sharp reflexes.

Long-term side effects (those that affect you after consistent cannabis use) can include depression, anxiety, and dependence on or addiction to cannabis products. If you typically consume cannabis by smoking it, other long-term effects, including chronic cough, bronchitis, and lung infections, can also occur. Patients can avoid these effects by choosing other methods of administration, such as vaporization, ingestible oils, oral sprays, and capsules.

In some cases, long-term cannabis use can cause a disorder called cannabinoid hyperemesis syndrome. Its symptoms including nausea, vomiting, and colicky abdominal pain that the patient can relieve temporarily by taking hot showers, or permanently by ceasing all cannabis use. Abrupt discontinuation of cannabis may cause withdrawal effects and the best method of stopping cannabis should be discussed with your health care team.

In addition, there are certain individuals who should avoid cannabis products, whether recreational or medicinal. This includes pregnant women, because we don’t have enough evidence to know how cannabis affects a developing fetus. Individuals with a personal or familial history of mental illness should also try to avoid cannabis, as it might exacerbate certain mental health syndromes. In general, it is very important that children and adults younger than 25 years-of-age don’t consume cannabis, as there is some evidence that cannabis intake can affect brain development. However, in children with severe seizure disorders (epilepsy), a neurologist or other neuro-specialist might recommend cannabis products that are high in CBD to reduce seizure frequency and severity. This is usually only done in cases where the epilepsy is so severe that getting the seizures under control is more important than any potential risks from cannabis and other pharmacological treatment options have been tried or considered.

Cannabis can also interfere with your ability to make sound decisions and judgements, so it is important to avoid risky behaviour to prevent accidents. One other thing to be aware of is the interaction potential between cannabis and other medications, which can lead to increased or decreased blood-levels of various medications. Make sure to speak with your physician, pharmacist, or nurse practitioner if you are taking other medications along with cannabis.

Overall, medical cannabis is generally safe. It has virtually no overdose potential, so it does not lead to overdose death, but it is important to be aware of the potential side effects and complications, which might lead to fatal accidents in individuals who behave recklessly while using cannabis.

10 Questions to Ask Your Health Care Team About Medical Cannabis

  • Is cannabis an effective and safe choice for me?

  • What dosage and type of cannabis should I take?

  • What would be the best method of administration for my needs?

  • Will cannabis interact with any of the medications I am currently taking?

  • Do I have any insurance coverage options for medical cannabis?

  • What side effects are likely, and what can I do to reduce this?

  • Can I use it safely during pregnancy or breast feeding?

  • Are there potential interactions between cannabis and my other illnesses?

  • Will I still be able to access medical cannabis after recreational cannabis is legal?

  • If I choose to use medical cannabis, what steps do I need to take to begin and continue therapy?

Accessing Medical Cannabis

Going forward, with legal recreational cannabis in play, it is important to ensure that patients still have ready access to medicinal cannabis through their health care team. This should include consultations on dosing and strain type with a physician, pharmacist, or nurse practitioner trained in medical cannabis. Patients who require cannabis as a treatment for their disease or disorder should have access to cannabis from their health care providers and should not have to guess at what to buy from a recreational dispensary.

If you wish to try using medical cannabis, speak with your health care practitioner. You can get a medical authorization document from health care professionals, which you can use to purchase cannabis through licenced medical sellers rather than recreational sellers. While some physicians are wary about prescribing cannabis, many are comfortable doing so. If your physician doesn’t want to prescribe cannabis, then you can request a referral to a health care provider who will take your symptoms and disease into account and provide an appropriate dosage recommendation. When using medical cannabis, always follow the advice and recommendations of your health care team and make sure cannabis use aligns with the other prescription treatments you are taking.

Did You Know?

  • According to some research, men and women use and experience cannabis quite differently. Men are generally more likely to use and be dependent on cannabis,15 and they are more likely to report positive effects such as improved memory and increased musicality. Men are more likely to use joints, bongs, and vaporizers, while women are more likely to use pipes and edibles/tinctures/capsules. In addition, women are more likely to use cannabis medicinally in order to treat irritable bowel syndrome, migraines, anxiety, loss of appetite, and nausea.16

  • Cannabis was the first product to be traded online. In 1971, students at Stanford University negotiated the sale of ‘weed’ to students at Massachusetts Institute of Technology using ARPANET, an early network that became part of the basis of the modern internet.

  • Bhang is a drink that people in India have consumed in some variation for thousands of years, often during a Hindu spring festival called Holi. Making bhang involves taking leaves and buds from the cannabis plant, grinding them up, and combining them with milk, sugar, nuts, spices, and rose water, cooking until combined, straining, and then chilling it to serve as a cold beverage.

  • The word canvas comes from the term cannabis, which originated as the Latin word for hemp (based off the Greek κάνναβη). Historically, canvas was made from sturdy hemp fibres.

  • In what is now China, archeologists uncovered the grave site of a man who died 2,700 years previously, and was buried along with 28 ounces of cannabis.17 Also in what is now part of China, archeologists uncovered the burial site of a man from the same time period who had a shroud of 13 cannabis plants placed over his torso.18

  • While rare, some individuals are allergic to cannabis. Symptoms are similar to other allergies, and can include itchy and watery eyes, sneezing, runny nose, rashes, hives, wheezing, shortness of breath, and even anaphylaxis.

Photos: rexmedlen | & OpenClipart-Vectors |
1. Stockwell GA. Indian Hemp (Cannabis indica seu sativa). Scientific American. Supplement No. 1174. July 2, 1898. Available at: Accessed 2018-08-21.
2. Alger BE. Getting high on the endocannabinoid system. Cerebrum. 2013;2013:14.
3. Ahmed W et al. Therapeutic Use of Cannabis in Inflammatory Bowel Disease. Gastroenterology and Hepatology. 2016;12(11):668-679.
4. Corey-Bloom J et al. Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial. Canadian Medical Association Journal. 2012;184(10):1143-50.
5. Ware MA et al. Smoked cannabis for chronic neuropathic pain: a randomized controlled trial. Canadian Medical Association Journal. 2010;182(14):E694-701.
6. Ostadhadi S et al. Therapeutic potential of cannabinoids in counteracting chemotherapy-induced adverse effects: an exploratory review. Phytotherapy Research. 2015;29(3):332-8.
7. Szaflarski JP et al. Cannabis, cannabidiol, and epilepsy–from receptors to clinical response. Epilepsy and Behavior. 2014;41:277-82.
8. Naftali T et al. Treatment of Crohn’s disease with cannabis: an observational study. The Israel Medical Association Journal. 2011;13(8):455-8.
9. Lahat A et al. Impact of cannabis treatment on the quality of life, weight and clinical disease activity in inflammatory bowel disease patients: a pilot prospective study. Digestion. 2012;85(1):1-8.
10. Keyhani S et al. Risks and Benefits of Marijuana Use: A National Survey of U.S. Adults. Annals of Internal Medicine. 2018. doi: 10.7326/M18-0810.
11. Nielsen S et al. Opioid-Sparing Effect of Cannabinoids: A Systematic Review and Meta-Analysis. Neuropsychopharmacology. 2017;42(9):1752-1765.
12. Borgelt LM et al. The pharmacologic and clinical effects of medical cannabis. Pharmacotherapy. 2013;33(2):195-209.
13. Kim D et al. Inverse association of marijuana use with nonalcoholic fatty liver disease among adults in the United States. PLoS One. 2017;12(10):e0186702.
14. Government of Canada. Health Effects of Cannabis. Available at: Accessed 2018-08-20.
15. Canadian Centre on Substance Use and Addiction. August 2017 Canadian Drug Summary. Available at: Accessed 2018-08-21.
16. Cuttler C et al. Sex Differences in Cannabis Use and Effects: A Cross-Sectional Survey of Cannabis Users. Cannabis and Cannabinoid Research. 2016;1(1):166-175.
17. Russo EB et al. Phytochemical and genetic analyses of ancient cannabis from Central Asia. Journal of Experimental Botany. 2008;59(15): 4171–4182.
18. Jiang H et al. Ancient Cannabis Burial Shroud in a Central Eurasian Cemetery. Economic Botany. 2016;70(3):213–221.