In June's edition of the UKs British Medical Journal in editorial on the use of cannabinoids in medicine is published. 

The place of cannabis as a prohibited and purely harmful psychoactive substance should change. Evidence supports the kind of reform already occurring in US states and internationally. The UK is lagging behind. Doctors should be free to provide advice on the benefits and harms of medicinal cannabinoids

Here is the publication in full: Source Article Here



Cannabis as medicine BMJ 2017; 357 doi: (Published 16 May 2017) Cite this as: BMJ 2017;357:j2130

Giles Newton­-Howes, senior lecturer Department of Psychological Medicine, University of Otago, Wellington, New Zealand

Evidence supports reform to allow the legitimate study, regulation, and prescription of therapeutic cannabinoids

From its first recorded uses in China through to the early 20th century, cannabis has had a place in the pharmacopoeia. Queen Victoria’s personal physician, Russel Reynolds, opined in the Lancet in 1890, “Indian hemp, when pure and administered carefully, is one of the most valuable medicines we possess.”1 This opinion was based on current best evidence: the careful and documented observation of its effects in medical conditions.

In a similar vein, calls have been made to reconsider the role of cannabis in today’s society. Two well informed British politicians recently told The BMJ, “We have heard striking testimonies from patients… that cannabis has ‘given them their life back.’”2 Added to this, the international position on cannabis as a potential medication has changed, with international agencies and many governments relaxing a prohibitionist stance.

Internationally, there has been an important shift away from prohibitionism, allowing cannabis to be used for both medical and recreational purposes. The conflation of these two uses, however, confuses therapeutic application. A multitude of legislative and policy positions are possible for cannabis, from complete prohibition through to regulated legal supply (as occurs with alcohol). For strictly pharmaceutical use, however, the choice is binary: either it is licensed like any other medicine or it is not.

Cannabis is now available for medical uses in 29 states in the US (although illegal at federal level), Canada, the Czech Republic, and Israel but decriminalised far more widely. Decriminalisation allows doctors to discuss the risks and benefits of use in much the same way they might for any medicine: within their area of expertise and the evidence available, according to GMC guidelines.3

The central importance of evidence in the practice of medicine is now well established. Doctors must discuss the benefits and risks of management options with patients so they can make an informed choice. This presupposes that the medication under consideration is a uniform substance with reproducible pharmacokinetic properties. Cannabis, however, refers to a genus that includes a large number of flowering plants, of which C sativa is best known. This diversity of product is a major problem in the published literature on cannabis. Furthermore, the illegal nature of cannabis has made quantifying the use of the psychoactive compounds—predominantly Δ9-tetrahydrocannabinol and cannabidiol—nearly impossible. Medicinal cannabinoid is one suggested solution to help clarify discussions4; the other is to use a company trade name to ensure specificity.

Within this limitation, substantial progress has been made in the evidence underpinning medicinal use of cannabinoids. Moderately strong evidence supports the use of medicinal cannabinoids by patients with chronic pain or spasticity.5 Evidence is weaker for other conditions, including epilepsy. Two recent reviews both concluded that an effect on epilepsy in humans is biologically plausible but the data from human trials are “extremely limited.”67

Cannabinoids have also been considered for the treatment of psychiatric conditions, although the potential for harm is greater in these patient groups. Epidemiological data identify statistically significant associations between psychosis, poor psychosocial outcomes, and cannabis use.8 The greatest potential for harm seems to be in early life,9where use is associated with psychosocial decline. Both trials and cohort studies suggest cognitive impairments that may not resolve with abstinence.10

A recent report by the US National Academies of Sciences Engineering and Medicine sets out the social, legal, and potential medical benefits of cannabis and its derivatives and makes four main recommendations. For the purposes of using cannabis as a medication these can be distilled to: “improve the clinical science” and “change the regulatory landscape to allow this to happen.”11 Notably, the report identifies the need for “research grade cannabis products,” with sufficient diversity to examine the individual psychoactive components of interest and their effects.

The place of cannabis as a prohibited and purely harmful psychoactive substance should change. Evidence supports the kind of reform already occurring in US states and internationally. The UK is lagging behind. Doctors should be free to provide advice on the benefits and harms of medicinal cannabinoids. There is a standard regulatory route for compounds to be licensed as medication, and there is no reason medicinal cannabinoids should not follow this route. As the view of cannabis in wider society shifts from illicit substance to accepted psychoactive agent, societies must also debate the introduction of cannabinoids as legitimate medicines, including how to best secure the necessary evidence and regulatory framework to deploy them safely.


  • Competing interests: I have read and understood BMJ policy on declaration of interests and declare that I am a member of the Pharmacology and Therapeutics Advisory Committee, and in this capacity have given paid advice about cannabinoids to PHARMAC, the New Zealand national government agency responsible for the public funding of medicines.

  • Provenance and peer review: Commissioned; not externally peer reviewed.


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  2. Meacher M, Clegg N. How changes to drug prohibition could be good for the UK—an essay by Molly Meacher and Nick Clegg. BMJ2016;357:i6006doi:10.1136/bmj.i6006.

  3. General Medical Council. Good medical practice. GMC, 2013.

  4. Newton-Howes G, McBride S. Medicinal cannabis: moving the debate forward. N Z Med J2016;357:103-9.pmid:27857243.

  5. Whiting PF, Wolff RF, Deshpande S, et al. Cannabinoids for medical use: a systematic review and meta-analysis. JAMA2015;357:2456-73. doi:10.1001/jama.2015.6358 pmid:26103030.

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  8. Hall W, Degenhardt L. Adverse health effects of non-medical cannabis use.Lancet2009;357:1383-91. doi:10.1016/S0140-6736(09)61037-0 pmid:19837255.

  9. Fergusson DM, Boden JM. Cannabis use and later life outcomes. Addiction2008;357:969-76, discussion 977-8. doi:10.1111/j.1360-0443.2008.02221.x pmid:18482420.

  10. Crean RD, Crane NA, Mason BJ. An evidence based review of acute and long-term effects of cannabis use on executive cognitive functions. J Addict Med2011;357:1-8.doi:10.1097/ADM.0b013e31820c23fa pmid:21321675.

  11. National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. National Academies Press, 2017. doi:10.17226/24625.