There's a lot of discussion in social media about the use of cannabis for pain. No doubt the 2020 referendum on cannabis legalisation and control has also had an influence. It's not always easy to know what information in the media is accurate. A recent New Zealand study looking at how chronic pain is represented in the media in New Zealand found that cannabis was reported as a ‘silver bullet’ for chronic pain relief, despite limited evidence for this. Also, it found that only a few stories mention the side effects of medicinal cannabis.
A quick rundown on some terms
Cannabis refers to all the products derived from the plant Cannabis sativa. While cannabinoid refers to a group of substances found in the cannabis plant. There are well over 100 known cannabinoid substances. The main two are CBD (cannabidiol) and THC (tetrahydrocannabinol). Mammals (including humans) have what is called an endocannabinoid system. This system plays a part in a number of functions and processes in the body including sleep, mood, pain modulation, inflammation, learning and memory, muscle formation, bone remodelling and growth, skin and nerve function, cardiovascular system function. Our bodies make molecules called endocannabinoids and we have special receptors for these in our nervous system - CB1 and CB2 receptors. The endocannabinoids we produce bind to either receptor, depending on what function they are carrying out.
The International Association for the Study of Pain (IASP) has very recently released a statement on the use of cannabinoids to treat pain. Their statement comes out of work done by a taskforce that spent two and a half years looking at the available research on the use of cannabinoids for pain.
The upshot of this extensive piece of work is that there are currently not enough high-quality human studies to allow the IASP to endorse the general use of cannabis and cannabinoids for pain at this time. In one large study called a systematic review of randomised controlled trials (that's a study of many studies) which looked at 36 studies including a total of 7217 participants, they found that the quality of evidence was low to very low and there was a high risk of bias in the studies. Research is indicating promise, but many studies haven't been done on humans with pain. Much more evidence is needed to find out which people with pain will benefit the most, and also which people may experience the most harm. It can't be assumed that because a product is natural and has been used for therapeutic purposes over millennia, it is beneficial for ALL people or ALL types of pain.
The IASP have done an easy-to-read summary of the main points (link below), which is worth a read if you have been considering or are using cannabis or cannabinoids for pain management. Given that this is a growing area of discussion and more and more information is appearing in social media about the use of cannabis and CBD for pain (much is not evidence-informed and is mainly aimed at product promotion), it is really important to be well informed with reliable information as it helps people make better decisions. It will be interesting to see what emerges from more good quality research over time.
Update 26/4/21: The Faculty of Pain Medicine, (Australian and New Zealand College of Anaesthetists) has recommended against prescribing currently available medicinal cannabis products to treat chronic non-cancer pain unless part of a registered clinical trial. This is also based on the current lack of high-quality studies, issues of harms in relation to interactions with other medications patients may be on, and the reality that cannabidiol-only formulations that are the most prescribed products at present have not been studied under randomised controlled trial (RCT) conditions for pain.