From February 2021, Australians will technically be able to buy low dose cannabidiol (CBD) products over the counter from a pharmacist. The thing is, although the Therapeutic Goods Administration (TGA) has determined CBD is unlikely to be harmful — thus justifying use without prescription — at the moment there are no actual products approved for sale. Cannabidiol is certainly coming though, with several companies racing to provide the specific safety, quality, and efficacy data to gain TGA approval.
So, is the science behind CBD oil sound enough to justify its use? Here’s what we’ve found in the research.
What is CBD?
Cannabidiol is a type of chemical compound called a phytocannabinoid, which is produced by Cannabis plants. Unlike tetrahydrocannabidiol (THC), the phytocannabinoid responsible for the psychotropic effects of marijuana, CBD does not cause intoxication.
The pharmacological mechanisms of CBD action are complex. Unlike THC, CBD has minimal action on the body’s cannabinoid receptors (CB1 and CB2) but modulates endogenous cannabinoid action and other cell signaling mechanisms1.
What are the proven health benefits of CBD?
Experiments show beneficial effects of CBD in animal models of human disease, including Alzheimer’s, Parkinson’s and Huntington’s diseases, multiple sclerosis, pain, anxiety, depression, cancer, and various inflammatory diseases and processes1. Less evidence is available from studies in humans with these actual diseases2.
There is some evidence to suggest that CBD can reduce symptoms of anxiety and schizophrenia but, to date, the only approved use of CBD is for seizure management in Lennox-Gastaut and Dravet syndromes3.
There is growing public interest in the potential for CBD as an ‘alternative therapy’ for pain relief. There is even the suggestion that CBD may be a useful alternative to opiates and a treatment for opioid dependence or addiction4. However, there is not a lot of high-quality evidence demonstrating an analgesic effect of CBD.
The unregulated status of CBD in the USA until recently complicated assessments of CBD effectiveness there, for treating disease. The various CDB preparations contain all sorts of other components (including large amounts of THC in some cases). There have been very few clinical trials of pure CBD, and its lack of availability in other countries (like the UK and Australia) has further limited research.
In the absence of strong evidence for efficacy, knowing the adverse effects of CBD might be the deciding factor for some people. The reported side effects of CBD include somnolence, fatigue, gastrointestinal upset, and impaired liver function3 and t TGA’s own review of CBD states that “the range of potential medicines that could be affected was wide ranging”5.
When CBD products eventually arrive on pharmacy shelves, evidence-based information about their effective use, side effects and contraindications may end up lagging behind.
1Pisanti et al. 2017. Cannabidiol: State of the art and new challenges for therapeutic applications. Pharmacology & Therapeutics, 175, 133–150.
2White 2019. A Review of Human Studies Assessing Cannabidiol's (CBD) Therapeutic Actions and Potential. The Journal of Clinical Pharmacology, 59 (7), 923–934.
4Hurd and O’Brien 2018. Molecular Genetics and New Medication Strategies for Opioid Addiction. American Journal of Psychiatry, 175 (10), 935–942.