Broadly speaking, medicinal cannabis is cannabis prescribed to relieve the symptoms of a medical condition, such as epilepsy. It’s important to distinguish between medicinal and recreational cannabis. Recreational cannabis is the form that people use to get ‘high’. 1
For some people with chronic or terminal illnesses, conventional medicines don’t work, or don’t work as effectively as medicinal cannabis. Also, for some patients, conventional medicines may work but cause debilitating side effects that cannabis can help to relieve. 2
Other types of cannabinoids
- Butane hash oil
- Synthetic cannabinoids
What are cannabinoids?
The main psychoactive ingredient of cannabis is tetrahydrocannabinol (THC), which acts on specific receptors in the brain known as cannabinoid or CB1 receptors. 3
Research has found that the cannabis plant produces between 80 and 100 cannabinoids and about 300 non-cannabinoid chemicals. The two main cannabinoids that have therapeutic benefits are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). There have been claims that other cannabinoids have therapeutic properties, but these have not yet been proven. 1
The main difference between the two cannabinoids is that THC has strong psychoactive effects, meaning it makes a person ‘high’, whereas CBD is thought to have an anti-psychoactive effect that controls or moderates the ‘high’ caused by the THC. CBD is also thought to reduce some of the other negative effects that people can experience from THC, such as anxiety. 4
The psychoactive effects of THC, such as euphoria and feeling relaxed or sleepy, are well known, but it also has analgesic, anti-inflammatory and antioxidant properties, as well as preventing and reducing vomiting. 1
Research is being conducted into CBD for its potential to treat epilepsy, schizophrenia and other psychotic disorders, type 2 diabetes, inflammatory bowel disease, some tumours, and drug dependency. 1
The endocannabinoid system
The endocannabinoid system is a unique communications system in the brain and body that affects many important functions. 5 It’s made up of natural molecules known as cannabinoids, and the pathways they interact with. Together, these parts work to regulate activities like mood, memory, sleep and appetite. It is thought that medicinal cannabis can treat various illnesses by acting on the endocannabinoid system. 6
Types and forms of medicinal cannabis
There are three main forms of cannabis that can be used medicinally:
- Pharmaceutical cannabis products that are approved by an organisation such as the Therapeutic Goods Administration (TGA), including nabiximols (Sativex®) and synthetic cannabinoids such as Dronabinol®. Sativex, which comes as a nasal or oral spray, has been approved in over 24 countries for treating spasticity due to multiple sclerosis.
- Controlled and standardised herbal cannabis (plant products), such as the products produced in the Netherlands.
- Unregulated and illegal herbal cannabis (plant products), which contains unknown concentrations of cannabinoids and potentially harmful impurities such as bacteria and mould (USA only). 7
Why smoking cannabis for medical purposes is not recommended
Some people claim that smoked cannabis should be considered as a treatment for various medical conditions or even as a cure for cancer. However, there are two major concerns.
Firstly, smoking is a particularly harmful way of taking cannabis, mainly because carcinogenic substances are inhaled directly into the lungs. Smoking cannabis is not recommended by health authorities, as the smoked form contains at least 50 of the same carcinogens as tobacco. 8
Secondly, the majority of medicines used in Australia are produced under strict conditions. That way, doctors who are prescribing them (as well as people who are using them) know exactly what’s in them.
It’s important that doctors know that medicines have been tested and that each dose is the same. This means doctors can monitor the effects of a drug and doses can be adjusted according to a patient’s needs.
When recreational cannabis is used as medicine, doctors and patients can’t be sure of how strong it is or what mix of chemicals is in it. Consequently, one dose will never be the same as another. 8
There is a community need for medicines and therapies that can help to alleviate the painful symptoms of various illnesses and diseases.
An increasing number of studies suggest that medicinal cannabis in the form of oral extracts, sprays or pills can reduce pain and help treat some illnesses. However, as with many other drugs, medicinal cannabis can also cause unwanted side effects, such as difficulty concentrating, dizziness, drowsiness, loss of balance, and problems with thinking and memory. 9,10
Special Access Scheme
Under the TGA Special Access Scheme, some forms of medicinal cannabis are available. The scheme allows the import and supply of an unapproved therapeutic good to individual patients on a case-by-case basis.
Recently, the TGA has made changes to its Special Access Scheme to make it easier for medical practitioners to prescribe cannabis-based medicines for patients in need, under certain conditions.
Legislation that allows cannabis to be grown for medical or scientific purposes in Australia has been passed by the federal government.
In October 2016, the Commonwealth Government started a national licensing scheme for the cultivation and manufacture of medicinal cannabis and controls all its regulatory aspects.
Manufacture is a joint responsibility between the Commonwealth and the states and territories. Access to any cannabis products manufactured under the scheme is also a joint responsibility, with supply controlled by the provisions in the Therapeutic Goods Act 1989, which works in tandem with state and territory drugs and poisons legislation. 10,11
Don't expect your doctor to prescribe CBD, says physicians' college
Lack of medical evidence supporting CBD means doctors aren't going to suggest it, says Dr. Linda Inkpen
Demand is high for CBD products but there isn't yet much medical evidence backing their use, which means doctors in Newfoundland and Labrador aren't likely to prescribe or recommend them as a medical treatment.
As with any other medication, physicians must have the expertise and experience to authorize the use of CBD for their patients, says Dr. Linda Inkpen, registrar at the College of Physicians and Surgeons of Newfoundland and Labrador.
Even if they feel qualified to suggest CBD, doctors must ensure conventional therapies have been tried and assess for addiction risk before authorizing a treatment that lacks clinical backing.
"That's what we hold our physicians accountable to in the interim until we find out exactly what we're dealing with, and it's what our patients should expect," Inkpen told CBC Radio's On The Go.
Across the province, customers going to licensed cannabis retailers in search of CBD products are leaving disappointed — supply hasn't been able to keep up with demand.
CBD or cannabidiol is, like THC, a cannabinoid, which is a naturally occurring compound in the cannabis plant. Unlike THC, CBD doesn't make you high, but many people have reported anecdotally that using high-CBD cannabis or CBD extracts has helped them with everything from anxiety to pain relief.
As a result, the demand for CBD products has exploded across the country, but demand is outstripping supply. A spokesperson for the province's liquor corporation, which also oversees recreational cannabis sales, previously told CBC News it has been hard to keep CBD products in stock, and two retailers confirmed demand for the products is high.
CBD is sold via the recreational cannabis market, but those retailers are prohibited by law from making health claims or providing medical advice about cannabis products. Some patients have looked to their physicians and the medical cannabis market, but they are unlikely to have CBD prescribed via that route, Inkpen said.
"The college's stance is the same as the other colleges right cross the country," she said.
"We are cautioning patients and physicians who choose to either authorize use of these products, or patients who choose to use them, to be very, very cautious and careful until the evidence is in of what the short-term and long-term benefits might be for these products, and what the short-term and long-term disadvantages might be."
Lack of research so far
Right now, there just isn't enough information on those potential harms and benefits, Inkpen said. Research has been limited on cannabidiol because of the legal issues around the cannabis plant, especially in the U.S.
Even in countries like Canada, where some research on cannabis has been done, results could still be years away.
"Medical research takes time," Inkpen said. Studies go though multiple phases, from laboratory to animals and then humans, and each one can take months or years. Information about longer-term harms and benefits takes even more time.
Inkpen said she recently looked into ongoing research on CBD and found there were more than 60 short-term and long-term research studies currently underway worldwide, looking at 23 different diseases or conditions. About a third of those studies were based in Canada, she said.
What patients should know
In the absence of prescribing physicians and completed medical research, some people might be taking matters into their own hands.
In the months leading up to cannabis legalization, the college heard more often from patients wondering where they could be prescribed cannabis product, Inkpen said. Since Oct. 17, those calls have decreased.
She can't say if that means people are instead visiting recreational cannabis retailers to buy CBD for non-recreational use, but Inkpen acknowledged that could be the case.
But while cannabidiol doesn't have the psychoactive effects of THC, there are four categories of people who are particularly advised to exercise caution with the use of cannabis, she said: those with ongoing chest conditions like asthma, if using an inhaled cannabis product; people who are pregnant; people with ongoing mental health conditions, or the propensity for them; and those with addictions, or the propensity for them.
"There's a lot of anecdotal information out there right now that might be of some concern when using these products with them," Inkpen said.
Additionally, people who are using over-the-counter products, including cannabis, should make their physician or nurse practitioner aware in case of any potential reactions with prescribed treatments, she said.
And Inkpen suggested referring to the Health Canada website for information and updates as people wait for further guidance from the results of ongoing research into CBD and its potential harms and benefits for a variety of conditions.
"I would have to refer members of the public, and our prescribers as well, to please be guided by what Health Canada has been doing and continues to do, and what information and research is happening worldwide on this particular substance."
Cannabis-based Medicinal Products Medicinal Marijuana
Since a change in the law in November 2018, some cannabis-based medicines have been available on prescription. However, there is only evidence of benefit for treating a small number of conditions.
Many cannabis-based products are also available to buy online, without a prescription, but the quality and content of these products is not known. Most of these products, including those called ‘CBD oils’, are illegal to possess or supply. Also the exact quality and content of these products is usually not clear and they may not be safe to use.
Some health stores also sell certain types of ‘pure cannabidiol (CBD)’. However, they tend to only contain very small amounts of CBD, so there is little evidence of any benefit, and there’s no guarantee these products will be of good quality.
Cannabis-based Medicinal Products
In this article
What are cannabis-based medicines?
Cannabis-based medicines (CBMs) are medicines derived from cannabis that have been used for treating medical conditions. CBMs contain cannabinoids derived from the cannabis plant, including delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD), or a combination of THC and CBD. THC is the constituent of cannabis that causes the ‘high’, whereas CBD is not intoxicating at typical doses. THC is more likely than CBD to cause side-effects.
Man-made (synthetic) cannabinoids are also available. They mimic the effects of specific cannabinoids such as THC.
What conditions can cannabis-based medicines be used to treat?
CBMs have been studied in a variety of different conditions but there is currently only evidence of benefit in a few conditions. Therefore only a few people are likely to get a prescription for medical cannabis. Currently, CBMs are only prescribed for the following conditions:
- Adults with nausea or vomiting caused by chemotherapy.
- People with muscle stiffness and spasms caused by multiple sclerosis (MS).
- Children and adults with rare, severe forms of epilepsy.
There is currently no evidence of benefit using CBMs for any other condition such as chronic pain or fibromyalgia.
Nausea and vomiting caused by chemotherapy
Chemotherapy may cause a person to feel sick (nauseous) or vomit. Nabilone is a man-made (synthetic) CBM that can be prescribed by a specialist to help relieve these symptoms, but only when other treatments have not helped or are not suitable.
Muscle stiffness and spasms caused by multiple sclerosis
Nabiximols (Sativex®) is a CBM that is sprayed into the mouth. In the UK, it is licensed for people with MS-related muscle spasticity that has not improved with other treatments.
Severe treatment-resistant epilepsy
Epidyolex® is a highly purified liquid containing cannabidiol (CBD). It will not get you high, because it does not contain tetrahydrocannabinol (THC), the chemical in cannabis that makes you high. Epidyolex® can be prescribed for patients with Lennox-Gastaut syndrome or Dravet syndrome, which are both rare types of epilepsy.
What are the side-effects of cannabis-based medicines?
The risks of using CBMs containing THC (the chemical that gets you high) are not currently clear. Ongoing clinical trials are needed before they can be used safely. ‘Pure’ products that only contain CBD, such as Epidyolex®, do not carry these unknown risks linked with THC. However, most products will contain a certain amount of THC. The main risks of THC cannabis products are:
- An increased risk of a psychotic illness such as schizophrenia.
- Dependency on the medicine (addiction). This risk is probably small when its use is controlled and monitored by a specialist doctor. The risk increases with increasing levels of THC.
Cannabis bought illegally off the street, with unknown quality, ingredients and strength, is the most dangerous form to use.
The other possible side effects of CBMs are:
- Poor appetite
- Feeling sick
- Change in behaviour or mood
- Feeling very tired
- Feeling ‘high’
- Suicidal thoughts
Like many other medicines, CBMs can also affect how other medicines work. Always discuss possible interactions with a specialist. CBD can also affect how your liver works, so doctors would need to monitor you regularly.
How can you get a prescription for a cannabis-based medicine?
You cannot get a prescription for a CBM from a GP. A CBM can only be prescribed by a specialist hospital doctor. The specialist will advise trying other treatment options first, before considering a cannabis-based product. A prescription for medical cannabis would only be given when it was believed to be in your best interests, and when other treatments had not worked or were not suitable.
After the initial prescription, further prescriptions for CBMs may be issued by another doctor as part of a shared care agreement under the direction of the initial specialist prescriber.
What else do you need to know?
Before being prescribed a CBM, the following should be discussed with you: