Why Did the ACMD Say Evidence Would Take Several Years After 2018?

In November 2018, the UK government made a landmark change in cannabis regulation by rescheduling cannabis-based products for medicinal use. This move sparked hope among patients, clinicians, and advocates keen to see wider access to these treatments on the NHS. Yet, despite the fanfare, the Advisory Council on the Misuse of Drugs (ACMD) cautioned in their subsequent reviews that accumulating solid evidence on effectiveness and safety would take "several years."

This blog post unpacks why the ACMD took this careful stance, clarifying what the 2018 rescheduling actually changed, the ongoing distinction between legal prescribing and NHS funding, and the complexities behind specialist-only prescribing rules, especially relating to unlicensed cannabis-based medicines. We also explore the key ACMD reports, including the notable November 2020 conclusion, and offer guidance on navigating the current UK medical cannabis landscape using trusted resources like medicalcannabis.co.uk and releaf.co.uk.

What Changed in 2018? The Cannabis Rescheduling Explained

Before November 2018, cannabis and its derivatives were classed under Schedule 1 of the Misuse of Drugs Regulations 2001, meaning they were considered to have no therapeutic value and were illegal to prescribe medicinally. This effectively blocked any NHS prescriptions or legal medical use of cannabis-based products.

The rescheduling in November 2018 reclassified cannabis-based products for medicinal use nhs commissioning cannabis medicine (CBPMs) to Schedule 2 but only when prescribed by specialist physicians in specific circumstances. This legal shift meant:

Clinicians with specialist credentials could legally prescribe cannabis-based medicines.
Patients could receive these medicines without breaching drug laws.
The NHS was not obliged to routinely fund these prescriptions; affordability remained a separate issue.

In one sentence: Before 2018, medical cannabis was illegal to prescribe; the rescheduling made legal prescribing possible but did not guarantee NHS funding or wide access.

The Legal vs Funding Divide: Why NHS Access Remains Cautious

One of the most frequent misunderstandings is confusing legal prescribing with automatic NHS access. The 2018 change made medical cannabis legal to prescribe—but hospital trusts and NHS England decide whether to pay for the medicines. Many clinics online tout access as now “easy” or “available on the NHS,” which isn’t the whole truth.

As of mid-2024, NHS funding remains tightly restricted to very limited conditions and exceptional cases. This is in large part due to the ACMD’s and NICE’s cautious stance that more robust evidence is needed before widespread routine prescribing can be endorsed and funded.

Specialist-Only Prescribing: Why the Restriction?

The government’s decision to restrict prescribing to specialists came from concerns about clinical safety, variability in product quality, and uncertainty over effectiveness compared with licensed medicines. Only consultants with experience in relevant areas such as neurology, paediatrics, or pain management can currently prescribe CBPMs legally.

This arrangement aims to:

Ensure specialist scrutiny and patient safety.
Prevent off-label or inappropriate use.
Centralise data collection on outcomes to feed into evidence generation.

General practitioners (GPs) remain unable to initiate medical cannabis treatment under current UK rules, and many specialists remain cautious about prescribing cannabis-based medicines without more compelling clinical trial data.

Unlicensed Cannabis-Based Medicines and NHS Caution

Most cannabis-based medicines currently prescribed in the UK are unlicensed. This means they do not have full marketing authorisation from the Medicines and Healthcare products Regulatory Agency (MHRA), often due to a lack of large-scale clinical trial data submitted for approval.

Unlicensed medicines put clinicians in a grey area: they can prescribe them but take on more responsibility for monitoring safety and outcomes. The NHS generally prefers to fund licensed medicines with clear evidence bases, another reason medical cannabis remains a special case and not widely reimbursed.

Clinicians often rely on named-patient supply or private prescriptions to access these medicines. Patients considering these options can use sites like medicalcannabis.co.uk to research clinics and compare services.

Why Did the ACMD Say Evidence Would Take Several Years?

In their cannabis review published in late 2020, the ACMD explicitly stated that gathering robust clinical evidence on the risks and benefits of cannabis-based medicines would require "several years" of controlled real-world data and clinical trials. Several reasons explain this cautious timeline:

Novelty of Legal Prescribing: Prior to 2018, the lack of legal prescriptions meant limited UK-based clinical data. Systems to routinely monitor patient responses were not established.
Diverse Product Profiles: Cannabis-based medicines vary widely in THC and CBD content, formulation, and indication. This complicates safe, standardised study designs.
Regulatory Scrutiny: MHRA and NICE require high-quality randomised controlled trials (RCTs) to approve and recommend medicines. These trials take years to design, run, and analyse.
Variable Patient Outcomes and Ethical Challenges: Anecdotal evidence and observational data can be misleading. Well-conducted studies need time and resources.
Data Collection Infrastructure: Specialist clinics and NHS sites are still developing reporting frameworks to ensure consistent monitoring of effectiveness and adverse events.

In other words: even though legal prescribing began in 2018, building up reliable evidence takes time, rigorous science, and systematic patient follow-up.

The November 2020 ACMD Conclusion: What Did They Say?

The November 2020 ACMD report summarised their review of UK cannabis policy and medical evidence. Key points included:

Support for Current Specialist Prescribing: The ACMD agreed that prescribing cannabis-based products within specialist services was appropriate but should remain controlled.
Need for more robust data: They clearly stated that more independent research and real-world data would be needed to expand access safely.
Public Health Considerations: They noted the risk of unintended diversion and emphasised careful patient selection criteria.
Deferred Widespread NHS Adoption: The ACMD echoed the cautious NHS stance, implying it was premature to broadly fund medical cannabis prescriptions without further evidence.

The full report can be consulted, but the gist is: the ACMD saw the rescheduling as a stepping stone, not a green light to immediate mass access.

Price Transparency and Patient Access: What Patients Need to Know

No specific prices were stated in the ACMD reports or official NICE guidance. acmd 2025 work programme cannabis Pricing remains highly variable depending on the product, supplier, and whether prescribed privately or via the NHS.

If future sources quote prices, always look for exact quotes and official attribution before accepting costs as representative. As of now, typical private prescriptions for cannabis-based medicines can reach several hundred pounds per month, but official NHS funding remains limited to exceptional cases.

Patients navigating this complex landscape can use platforms like medicalcannabis.co.uk to compare clinic services, find specialists, and understand treatment costs. For clear, patient-centred explanations of indications, prescribing rules, and expectations, releaf.co.uk offers reliable, jargon-free guides.

Summary: What Does “Evidence Over Several Years” Really Mean for Patients?

In summary, the ACMD’s cautious timeline reflects the reality that scientific and regulatory validation takes time. The 2018 rescheduling unlocked legal prescribing but did not remove the need for evidence-based caution regarding safety, efficacy, and patient selection.

Until several years’ worth of high-quality data accumulate and NHS evaluation processes conclude, patients should understand that:

Legal prescribing is possible but restricted to specialists.
Most cannabis-based medicines remain unlicensed and therefore costly if accessed privately.
NHS funding is currently rare and limited to specific clinical scenarios.
Reliable evidence on benefits and risks continues to develop and will influence future access policies.

For those considering medical cannabis treatment, careful consultation with specialists and using resources like medicalcannabis.co.uk and releaf.co.uk remains the best way to navigate this evolving landscape while avoiding common misinformation.