Doctors' digest

Medical Cannabis & IBD

By Dr Daniel Couch MbChB PhD, Specialist Registrar in General Surgery

Everyone’s heard of cannabis, but not everyone knows the difference between recreational cannabis and medical cannabis, can you explain?

Cannabis is a product derived from the cannabis sativa plant and has been used by humans for centuries to treat a wide variety of symptoms. It’s famous for giving you a feeling of being “high,” and recreationally this has been its major use.  Many people have also found that using cannabis may help with their medical symptoms.  For many years in the UK the possession and selling of this plant has been and still is illegal.  So, to be clear possession of cannabis obtained from a “dealer” on the street is illegal.

However, there was a change in the law surrounding cannabis-based medicines that are prescribed by a medical specialist.  Hospital consultants can now prescribe what we would consider “medical cannabis” if certain conditions are met.  This use of “medical cannabis” is not illegal but is tightly controlled.

Is medical cannabis beneficial for IBD patients?

Many IBD patients state that their symptoms improve when taking medicinal cannabis.  However, when we look at the research which has been carried out to formally answer the question, we find that the jury is still out.  There has been a great deal of research looking into the effects of cannabis and cannabis-based medical products on IBD.  This research is split into preclinical or laboratory centered research and clinical or patient-centered research.  Almost all of the preclinical research suggests that cannabis-based medicines will be beneficial in IBD.  However, when looking at the clinical studies the research is unable yet to state whether cannabis-based medicines are actually of benefit.  The main reason for the deliberation that the clinical studies carried out have not been large enough to have firm conclusions.  In short, until we have larger, properly conducted clinical studies examining what matters we just don’t know.

Can medical cannabis reduce inflammation in IBD, or does it just help with symptoms?

Again, this is a really interesting and important question.  Most of the preclinical research shows that the two main chemicals in cannabis, THC and CBD, reduce inflammation when performing IBD experiments using test tubes, but we’re yet to know from the clinical research whether this is actually the case in patients walking around with IBD.  One interesting study looking at people with IBD using over-the-counter cannabis medicines in the US demonstrated that their symptoms were reduced, but over the course of a few years the progression to surgery for IBD was not actually reduced.  Unfortunately, that study had its faults and, again, we’re still waiting for more clinical research to see what the effect actually is for patients.

How would medical cannabis be used alongside conventional IBD therapies?

The prescribing of medical cannabis in the UK is not commonplace yet, but we know from Canadian practice that cannabis-based medicines are usually prescribed alongside conventional medicines such as azathioprine or mesalazine for example.  We’re definitely not at the stage where medical cannabis is being prescribed as a first-line therapy for IBD.  In the UK at least, it’s purely reserved as a last resort.

Is it legal in the UK and can any doctor prescribe it?

Previously no doctor in the UK could prescribe medical cannabis.  However, in November last year the law changed following the Billy Caldwell case.  Now any hospital consultant (a consultant specialist) can prescribe a cannabis-based medicine for the condition they regularly treat within their specialism.  Having said that, as cannabis-based medicines are relatively new and the evidence for their use limited, only a few doctors in the UK are comfortable with prescribing them.  This may change as new clinical research emerges.

What is the difference between medical cannabis and OTC cannabis oil?

Cannabis oil is an extraction of one of the main chemicals in cannabis – CBD or cannabidiol.  This chemical doesn’t get you high but may provide some anxiety reducing effects and may reduce inflammation.  The full clinical effects of CBD are not yet known.  Cannabis oil you can currently buy from a pharmacist or health-store is usually CBD suspended in an oil, such as coconut oil for example.  There’s very little regulation around the production and selling of CBD oil, and therefore the quality is highly variable.  Some CBD oils have more CBD in them than they state on the label, whilst some have none at all.

Cannabis-based medicines are a completely different entity.  The regulation around the production and selling of these prescription-only drugs is very tightly regulated.  The quality of these medicines is very high, and they must be thoroughly examined both in the lab and in clinical studies before they can be prescribed.  They contain CBD or THC , either alone or in combination with each other, and may contain other medicines.  These are the medicines which are only available through a hospital specialist.

Is CBD oil beneficial for IBD?

Due to the difference in quality between cannabis oils available, and the lack of clinical studies we just can’t say for sure.

Are there any side effects from taking medical cannabis?

It depends whether we’re talking about CBD or THC.  CBD medicines won’t give you a high, and don’t appear to have many significant side effects other than nausea at high doses.

THC does give you a “high” feeling though, and may also make you feel drowsy.  We should also mention that we don’t know what the effects of THC are on the childhood or adolescent brain.  It may also be the case that these two chemicals may interact with other medicines you are taking, giving unwanted side effects.  Because the prescribing of these medicines are not yet widespread, however, we really can’t say what the effects of these medicines are over long periods of time.

Can you drive after taking medical cannabis?

The DVLA haven’t yet released guidance on this.  Currently driving under the influence of recreational cannabis is illegal.  We are awaiting guidance from the DVLA on whether medical cannabis automatically stops you from driving.  We suspect that prescribed THC, as it may make you feel drowsy, may prevent you from driving, but CBD will not.

What are the long-term side effects of medical cannabis use?

In adults there have been no significant reports of harm when used in an observed setting.  There are some early reports that use during adolescence might be harmful, although we still need more research to determine if this truly the case in both adults and adolescents.  We are yet to determine if cannabis is actually addictive on a biological level, but the early indicators suggest that this isn’t the case.  This means that if you start being prescribed medicinal cannabis by your doctor it is very unlikely that you will become addicted.  If this is the case laboratory studies have suggested that the risk of this occurring is at a much lower rate than when taking opioid-based medicines.

Are there dosage instructions or do you just start slowly and build it up?

Most practitioners wouldn’t recommend just trying a random dose.  We know from prescriptions issued in Europe and Canada that micro dosing (starting with a very small dose) and working up seems to be the safest and most effective way of administering, but yet again we still need more research to determine the most effective dosage.

Are there any clinical trials for Crohn’s or UC?

There have already been several small trials examining this, and a larger, multi-centre trial is in the planning stages, which should enrol the first patients with the year.

How long will it take for a medical cannabis prescription to be easily obtained in the UK?

Some cannabis clinics are currently up and running in the private sector.  We are currently working with the department of health and other experts to bring about the rapid, safe prescribing of cannabis-based medicines in the NHS. We really want to get this right first time and therefore this process takes time.  If all runs smoothly we would hope to see the first NHS prescriptions in the next 18 months.

About the author

Dr Daniel Couch  MB ChB MRCS MBA PhD

Dr Daniel Couch MB ChB MRCS MBA PhD
Specialist Registrar in General Surgery

Dr Daniel Couch  has a  PhD in cannabinoid medicinal pharmacology, has 12 years of clinical experience and regularly treats  patients with IBD.  He is an international speaker in cannabinoid medicine and policy and has written 13 scientific publications featuring the role of cannabinoids in health & disease.  Dr Couch was the highest achieving graduate in MBA (Healthcare) from University of Nottingham 2018.  He has a special interest in cannabinoid medicine, clinical research and policy development and is medical advisor to the CMC UK.

The Crohn's and Colitis Charity


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