Cannabidiol, or CBD oil, is promoted for a wide range of medical conditions. Recently, a review for doctors weighed the science behind the claims.
The Clinicians’ Guide to Cannabidiol and Hemp Oils was published earlier this month in the journal Mayo Clinic Proceedings.
CBD is a compound found in the cannabis plant. It is not intoxicating, Health Canada said.
As consumer interest in CBD grows ahead of the Oct. 17 legalization of cannabis edibles, extracts and topicals, here’s a primer to answer common questions about its health claims for seizures, pain and other conditions.
What is CBD approved to treat?
Epidiolex, a purified form of plant-based CBD, is the only CBD-related treatment approved by the U.S. Food and Drug Administration (FDA). It is used to treat severe forms of epilepsy. Epidiolex isn’t listed in Health Canada’s database of medications approved for use in this country.
What is CBD commonly used for?
There are anecdotal reports from users of CBD helping with certain types of pain, such as nerve-related back pain.
“Chronic pain management continues to challenge patients and physicians alike, and investigation into potential therapies such as CBD and hemp oils is a promising area for the future of clinical pain management for both pain relief as well as addiction management,” Dr. Karen Mauck, an internist at Mayo Clinic, and her co-authors wrote.
Dr. Hance Clarke, director of pain services at Toronto General Hospital who wasn’t involved in the research, said he starts by asking patients what symptoms they want to use CBD to treat.
“The evidence has not caught up to the story that’s in the public,” Clarke said. “It’s tricky. It’s one of the first times in Canadian history where a medication has made it to the population without the science actually leading us there.”
Physicians need to work with patients to figure out what people are using, the levels in their body and what’s actually helped and what hasn’t.
“The world is looking to Canada over the next five to 10 years,” Clarke said. An evidence-based perspective on cannabis is needed rather than solely industry’s, he said.
Canada’s Arthritis Society said there’s limited clinical evidence so far on the relative benefits and risks of medical cannabis to treat osteoarthritis and rheumatoid arthritis. Dr. Gabriella Gobbi is a psychiatrist at McGill University’s faculty of medicine and the McGill University Health Centre.
In January, her research into CBD’s effects on pain and anxiety in lab rats was published in the scientific journal Pain.
“CBD now is widely used by people for all kinds of disease, in particular anxiety, panic attack, bipolar disorder, depression,” Gobbi said. “But we don’t know if CBD is really good for these kinds of diseases.”
Only clinical trials in humans can show if CBD is really effective for an illness, Gobbi said.
In Canada, pharmaceutical companies are sponsoring clinical trials to test CBD products in people.
How do you know what’s in the product?
Depending on what part of the plant is extracted, different components will be present in the oil, the Mayo Clinic authors said. Their list of what clinicians should look for include:
- Manufacturing standards certification, such as pesticide or herbicide testing.
- European Union, Australian or Canadian organic certification.
- Lab testing to confirm cannabinoid levels and the absence of heavy metals.
“We see variations from batch to batch where patients are doing well on something, and potentially the next time they seek that same product, potentially they’re not seeing the same effects,” Clarke said.
A research letter published in 2017 in JAMA found nearly 70 per cent of CBD extracts sold online were mislabelled.
“A lot of CBD oil can have very little or contain lots of THC [tetrahydracannabinol, the main psychoactive component in cannabis that gives users a high], so you must be very careful,” Gobbi said. “We need more quality control.”
What side-effects have been reported?
In larger studies on CBD treatment for epileptic patients, it was associated with drowsiness, decreased appetite and diarrhea in up to 36 per cent of people, the Mayo Clinic authors said, adding the side-effects were less severe and frequent compared with a conventional anticonvulsant medication.
The FDA said its review of a marketing application for Epidiolex suggested potential for liver injury associated with CBD.
“You can’t just self-treat,” Gobbi said.
What about drug interactions?
The main drug interactions doctors and pharmacists look for are drugs, such as morphine, oxycodone, sleeping pills, antidepressants or antipsychotics, that already make you sleepy, confused or impair co-ordination.
“If you’re taking those medications to begin with and you use cannabis, we’d expect that those side effects would get worse,” said Kelly Grindrod of the University of Waterloo’s School of Pharmacy.
People should talk to their physician, nurse or pharmacist to discuss potential drug interactions when determining whether to try CBD.
Maddie Brown, a registered practical nurse and cannabis consultant based in Ottawa, helps patients with medical cannabis prescriptions understand how CBD works and obtain it.
“I’m definitely most concerned about blood thinners,” Brown told CBC Radio’s White Coat, Black Art. “CBD can make Coumadin [a blood thinning medication] more potent.”
The general advice is to start low and go slow, especially if taking medications that are known to interact, Grindrod said.