The IASP published a review in 2021. There were 36 randomised controlled trials with 7217 participants. All trials had unclear or high risk of bias. The evidence was low or very low quality for the use of cannabinoids in any type of pain. The evidence to date neither supports nor refutes the use of cannabinoids or cannabis for pain. 36 randomised controlled trials involving 7217 participants. The IASP does not currently endorse the use of cannabis and cannabinoids for pain relief. The risk benefit trade off for pain is poor.
Stockings et al published a systematic review in 2018 of 47 RCTs and 57 observational studies. It is important to note that 48 of the studies were in neuropathic pain, and 7 were in fibromyalgia. The NNT for a 30% pain reduction is 24 (29% vs 26% for placebo). There was no difference between placebo for a 50% pain reduction. The standardised mean difference in pain is equivalent to a 3mm reduction on a 100mm visual analogue scale greater than placebo. The highest quality evidence is for neuropathic pain and multiple sclerosis related pain. There is low quality evidence for improved sleep, and patient global impression of change. There is no significant effect on physical functioning or emotional functioning.
In population studies, nonmedical cannabinoid is associated with psychosis, cognitive effects in adolescents and young adults, motor vehicle accidents, respiratory problems, and low birth weight in infants of cannabis exposed mothers. In RCTs for pain, common side effects are dizziness, sedation, and fatigue. The review by Stockings et al found that side effects were extremely common, occurring in 81%, compared to 66% compared to placebo, equating to a NNH of 6. There is also financial harm due to the very high costs of medicinal cannabis products in New Zealand.
CBD is non-psychoactive and non-addictive. Only 21 RCTs have been published without a single study on pain. There is zero evidence to support the use of CBD for pain. Adverse effects include liver injury, drug interactions, changes in alertness (somnolence or insomnia), gastrointestinal (diarrhoea &/or decreased appetite, abdominal pain, upset stomach), changes in mood (irritability & agitation).
There is some evidence for its use in rare childhood epileptic seizure disorders (Dravet syndrome, Lennox-Gastaut syndrome, and tuberous slerosis complex). The FDA has been very rapid with approving CBD when evidence has been published in these conditions, refuting conspiracy thinking around FDA approvals.
Substance Use Disorders
Globally and in Australasia the prevalence rate of cannabis substance use disorders is 290 per 100,000. This compares to an opioid use disorder prevalence of 353 per 100,000 globally, 415 per 100,000 in Australasia; and alcohol use disorder prevalence of 1321 per 100,000 globally, and 1305 per 100,000 in Australasia
Availability in New Zealand
At the time of writing, the only THC containing product available that doesn't require ministry of health approval is the Tilray FS Oral THC 10 : CBD 10 product. CBD containing products also do not require approval, and there are two brands available at the time of writing: Tilray and Medleaf. Pricing varies greatly, a (may not be up to date) pricing guide can be found here
- International Association for the Study of Pain presidential task force on cannabis and cannabinoid analgesia position statement. Pain 2021. . PMID: 33729207. DOI.
- Stockings et al. Cannabis and cannabinoids for the treatment of people with chronic noncancer pain conditions: a systematic review and meta-analysis of controlled and observational studies. Pain 2018. 159:1932-1954. PMID: 29847469. DOI.
- Hurd Leading the Next CBD Wave-Safety and Efficacy. JAMA psychiatry 2020. 77:341-342. PMID: 31940016. DOI.
- Cannabis Policies for the New Decade ”. US FDA presentation to US Congress, 15 January 2020.
- GBD 2016 Alcohol and Drug Use Collaborators The global burden of disease attributable to alcohol and drug use in 195 countries and territories, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. The lancet. Psychiatry 2018. 5:987-1012. PMID: 30392731. DOI. Full Text.