It’s been over four years since the UK legalised the medical use of cannabis. Despite this, attitudes towards its use remains a hot topic for patients and health professionals alike. Dr Simon Erridge from the Department of Surgery and Cancer separates fact from fiction about the prescribing of medical cannabis for health conditions such as chronic pain and anxiety.
Since 2018, medical cannabis has been available legally on prescription for patients here in the UK. However, many people are not aware of this and our research in 2021 suggested that almost 50% of UK adults are unaware that medical cannabis is legal in the UK. Many more may be unsure as to what medical cannabis is, when it can be prescribed, and what the medical evidence says about its effects. Despite this, there is a lot of promise held about the potential of medical cannabis and its use in healthcare in the future.
What is medical cannabis?
When speaking to people about my research, I often find the reality of medical cannabis in the UK is quite far removed from many of their preconceived ideas. The most common beliefs I hear is that medical cannabis is the same as cannabidiol (CBD) wellness products that you can buy from a health food shop or, on the other end of the spectrum, it is the same as cannabis that is obtained illicitly. Medical cannabis, rather than being the name of one specific medication, is the term used to refer to the broad range of products that can be manufactured using the flowering part of the cannabis plant. These medications can come in many forms, such as oils and capsules, but also as a dried flower. In addition, medical cannabis may contain CBD, tetrahydrocannabinol (THC), or any number of the over 450 compounds identified from the cannabis plant to date.
All medical cannabis products must adhere to pharmaceutical standards, just like any other medicine, to ensure their safety and consistency. This is one of the big differences between medical cannabis and the other products I mentioned. CBD wellness goods are treated like a food product and therefore the regulations around their production are much less strict, and studies suggest that the contents of CBD oils from certain manufacturers may vary markedly from their packaging. Illicit cannabis, on the other hand, obviously does not have to conform to any regulations. This presents risks because illicit cannabis can be contaminated with other substances and microbes, which can be particularly harmful to those with a weakened immune system. As there are an estimated 1.8 million people in the UK who are turning to illicit cannabis with the intention of treating health conditions, this is obviously particularly concerning for those individuals.
How is it prescribed?
The prescribing of medical cannabis is highly regulated in the UK. To be eligible for a prescription a patient must have previously trialled licensed medications for a health condition and either failed to receive sufficient benefit or the medication is not tolerated due to side effects. It is ultimately a last line measure for people with chronic health conditions. Moreover, the decision to start somebody on medical cannabis can only be made by a hospital consultant, with the support of other specialists. A significant proportion of the research we conduct at the Imperial Medical Cannabis Research Group aims to study the outcomes of people prescribed medical cannabis under these criteria. Using data from the UK Medical Cannabis Registry, which was developed by Sapphire Medical Clinics, we have now published 14 studies reporting the changes in health-related quality of life and adverse events reported by individuals prescribed medical cannabis. This type of research can be useful for doctors to help inform their current practice, but also in helping inform randomised controlled trials, which are the gold standard of medical evidence, to better assess the efficacy of medical cannabis.
What does the data show?
To date our research has shown that the most common conditions where medical cannabis is prescribed include chronic pain, anxiety, post-traumatic stress disorder, depression, and migraine. However, the largest proportions of these include chronic pain (~55%) and anxiety (~15%). Interestingly, over 70% of medical cannabis patients in the UK have consumed cannabis at some point in the past. Our most recent analysis, which included patients who had been followed up for up to 12 months, observed that patients, across all conditions where medical cannabis had been prescribed, reported changes in general health-related quality of life, anxiety, and sleep. Adverse events have only been reported 17% of individuals enrolled within the UK Medical Cannabis Registry.
Despite these promising outcomes there is a need to treat these results with some caution. Medical cannabis is not currently, and will never be, a panacea, and its use needs to be carefully considered on an individual basis. At present, whilst there is this growing body of evidence, it is still insufficient to make definitive statements on its efficacy and safety. Therefore it is important for there to be further research which will help us to understand if it warrants a larger role in healthcare in the UK, and if so which patients would be most likely to benefit.
Dr Simon Erridge is an Honorary Clinical Research Fellow in the Department of Surgery and Cancer’s Medical Cannabis Research Group. 
Thank you very much for being so thorough! I will be citing this article in a blog post at https://www.high-committee.co.uk soon and will of course give credit.