Decoding Cannabis: Introducing our new series on medical cannabis research

Each and every week, Decoding Cannabis will take a recent piece of medical cannabis research- be it a clinical trial, observational study, registry report, etc. - and unpack it in a way that’s relevant and easily understandable to UK medical cannabis patients.

We’ll look at what was studied, what the researchers found, and, most importantly, what it means for patients. Whether it’s a new finding on CBD for anxiety or inflammation, THC for chronic pain, mental health issues, or sleep - or long-term safety data - we’ll strip away the jargon and focus on what matters: clarity, context, and patient relevance.

This first post sets the stage. Here we outline the types of studies we’ll be covering, introduce some of the terms you’re likely to see, and share what you can expect from the series moving forward.

Evidence always matters, but it matters even more when it’s easily understood.

What kind of research will we explore?

Cannabis research isn’t one single thing - it spans everything from lab experiments to patient surveys, large-scale trials to registry reports. 

Some studies happen in controlled clinical settings. Others reflect how people use cannabis day to day, outside a lab, in the real world. Each offers a different kind of insight, and part of what Decoding Cannabis aims to do is make clear what kind of evidence we’re looking at, and why it matters for patients.

Each post in the Decoding Cannabis series will focus on a single study, report, or dataset. 

We’ll break it down using a consistent structure:

• What was studied and why it matters
• Who was included in the study (and who wasn’t)
• What the researchers found - positive, negative, or inconclusive
• What it means for patients, especially those prescribed cannabis in the UK
• What we still don’t know, and where research needs to go next

Randomised Controlled Trials (RCTs)

Often considered the gold standard in medical research, Randomised Controlled Trials (RCTs) test cannabis-based medicines against a placebo, with participants randomly assigned to each group. They help answer the question: does this work better than nothing at all? 

And while they're nothing short of rigorous, RCTs can sometimes exclude the more complex or long-term patients found in the real world.

Observational studies

Rather than testing a treatment under controlled conditions, these studies track what’s already happening - how patients are using cannabis, what symptoms improve, and what side effects appear over time. 

Observational studies are less controlled than RCTs, but, are often more relevant to real-world prescribing.

Systematic reviews and meta-analyses

These studies group similar trials or studies together and then analyse the data to look for patterns that may not emerge from a single study. 

If five studies show improvement, two show no change, and one shows a negative effect, a meta-analysis helps weigh that evidence and make broader conclusions which leads to better long term safety outcomes.

Case reports and case series

Individual medical cannabis patient stories can sometimes offer the first glimpse of something important. 

While these small reports can’t prove anything on their own, they often point to interesting effects, rare outcomes, or potential new applications for treatment.

Preclinical studies

These are early-stage studies carried out in labs, often involving cell or animal testing. Their goal is to understand how compounds (say cannabinoids or terpenes) interact with the body - things like how they affect inflammation, pain signalling, or brain activity. 

While preclinical studies can offer valuable clues, its important to emphasise they’re a starting point - not a final answer.

Cohort studies

Cohort studies are a form of observational research that follows a group of people over time. 

These studies help explore questions like: “Do patients taking medical cannabis for sleep report long-term improvements, or is it more of a short-term fix?” or “Can medical cannabis application positively affect a patient's quality of life for six, twelve, eighteen months - or is that effect ongoing?”.

Cross-sectional studies

These studies provide a snapshot at one point in time - surveying patients, for instance, about their current symptoms and medical cannabis administration. They’re useful for identifying broad patterns, but not for showing cause and effect.

Registry data

Real-world data from patient registries - such as Project Twenty21 or the UK Medical Cannabis Registry - offer some of the most detailed insights into how cannabis (both medical and recreational) is being used in the UK.

They’re also central to Releaf’s reporting. 

Our 2023 Say No to Pain surveyed over 4000 UK adults to get a better understanding of the wider public's current attitudes (and general understanding) concerning medical cannabis as a treatment for chronic pain. 

The findings were, in many ways, quite startling.

Despite becoming a fully legal treatment option in the UK back in November 2018, less than 1% of all potentially eligible UK patients have accessed medical cannabis. 

77% had direct experience with chronic pain, 47% didn’t know medical cannabis was a legal and effective treatment option, yet 61% of all respondents reported that they would consider medical cannabis if it had been recommended by a doctor.

All of this pointed to a clear gap between need, awareness, and understanding. In the two years since this report was released, we have published a medical cannabis blog every single business day (and continue to do so) to try and close that gap. 

White papers and policy reports

Not all useful evidence comes from journals. Government reports, think tank papers, and independent reviews can also provide helpful data - especially when it comes to access, regulation, and safety.

Narrative reviews

Written by experts in the field, these reviews offer a broad overview of a topic without the strict methodology of a systematic review. They’re helpful for context and identifying emerging trends, but less conclusive than primary research.

Key terms you’ll see throughout this series

You don’t need a science degree to understand cannabis research—but knowing a few key terms can make a big difference. These concepts come up often in studies and clinical guidance, and we’ll refer back to them throughout Decoding Cannabis.

THC and CBD

THC and CBD are the two major cannabinoids produced by Cannabis sativa L. plants. THC (tetrahydrocannabinol) is the main cannabinoid that can cause a ‘high’, but it also has a range of positive therapeutic associations, including pain relief, appetite modulation, and a sleep aid. CBD (cannabidiol) doesn’t cause intoxication and is typically prescribed for anxiety, inflammation, and seizure-related conditions.

The Endocannabinoid System (ECS)

The endocannabinoid system is the largest neurotransmitter system in the body and helps regulate a surprisingly extensive range of functions, including pain, mood, sleep, appetite, and more.

Cannabinoids like THC and CBD interact with this system to help restore balance.

Titration

Titration means slowly adjusting your dose to find the smallest amount that gives the best effect with the fewest side effects. It’s a key part of safe cannabis prescribing.

Bioavailability

A measure of how much of a substance reaches your bloodstream. For example, inhaled cannabis (via a dry herb vaporiser) is absorbed differently (and faster) than oils or capsules taken orally.

Full-spectrum vs Isolate

Full-spectrum products contain the entire cannabinoid and terpene spectrum produced by the source plant. Isolates contain only one cannabinoid - usually just CBD or THC.

Placebo effect

The placebo effect happens when someone experiences a benefit simply because they believe a treatment is working - even if the treatment has no active ingredient. This is why clinical trials often include a placebo group for comparison.

Side effects

Like any medicine, medical cannabis can cause side effects. These might include dry mouth, dizziness, changes in appetite, or feeling a slight intoxication effect - especially when starting treatment or adjusting your dose.

Dosing formats

Cannabis medicines come in various forms - like oils, capsules, or dried flower for vaporisation. Each has different absorption rates and durations. Studies often look at how these formats compare.

What we won’t do with the Decoding Cannabis blog series

We’re not here to make bold claims, cherry-pick results, or imply medical cannabis is a miracle cure. While it does offer significant benefits for many patients, the evidence varies depending on the condition, the formulation, and the individual.

This series won’t:

• Oversell early research or take findings out of context
• Promise outcomes that the evidence can’t support
• Skip over study limitations or uncertainty
• Assume that one format, dose, or cannabinoid is right for everyone
• Avoid complexity when it matters

Medical cannabis is an ever-evolving field, and the amount of research currently underway is growing every single year. Some studies are robust, others are early-stage or exploratory. When the evidence is strong, we’ll say so. When it’s mixed or limited, we’ll say that too.

We firmly believe that all UK medical cannabis patients deserve the full picture, not just the parts that sound good.

Final thoughts

To say that medical cannabis can be a life-changing treatment option truly is no exaggeration - but that doesn’t mean the science should be overstated or cherry-picked.

The reality is more nuanced. 

Some patients see dramatic results. Others see modest improvements. And for some, it may not help at all. That’s exactly why clear, honest communication around the evidence is so important - because decisions about your health should be based on what the research actually shows, not what someone wants it to say.

Decoding Cannabis exists to make that possible. One study at a time. 

If you’re interested in finding out whether you might be eligible for a UK medical cannabis prescription, head to our fast, free medical cannabis eligibility checker. It takes less than 20 seconds to complete and could be the first step towards better health and vastly improved quality of life.