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What Is Medical Cannabis? A Complete Guide for UK Patients
18 September 2025
What Is Medical Cannabis? A Complete Guide for UK Patients
Written by: IYOS Pharmacy Editorial Team
Originally published: 18 September 2025
Last updated: 2 November 2026
Editorial review date: 2 November 2026
Medical Cannabis at a Glance
Medical cannabis refers to cannabis-based products used for medicinal purposes. In the UK, certain cannabis-based medicinal products can legally be prescribed under strict medical and regulatory requirements.
Some are licensed medicines for specific conditions, while others are unlicensed products that may be considered in particular clinical circumstances.
Key facts about medical cannabis in the UK:
- Legal status: Certain cannabis-based medicines have been available on prescription under the relevant UK framework since 1 November 2018.
- Prescribing: Specific specialist-prescribing requirements apply to certain unlicensed cannabis-based medicinal products.
- NHS availability: Limited to particular medicines and clinical circumstances.
- Private prescriptions: May be issued following an appropriate specialist assessment, where clinically justified.
- Clinical evidence: The strength of evidence varies significantly between medicines and conditions.
- Patient safety: Potential side effects, interactions and individual medical circumstances must be considered.
- Pharmacy support: IYOS Pharmacy provides professional dispensing, prescription coordination and related pharmacy services.
Important: Medical cannabis is not suitable for everyone. An initial enquiry or eligibility assessment does not guarantee a prescription or particular treatment.
Introduction: Understanding Medical Cannabis in the UK
Medical cannabis has become an increasingly discussed subject in UK healthcare since changes to the law in November 2018.
Despite growing public awareness, there is still considerable confusion about what medical cannabis is, how it differs from recreational cannabis, which medicines are available and how prescribing works.
In the UK, cannabis-based medicinal products are subject to specific legal and professional requirements. Some medicines have been authorised for particular conditions, while others remain unlicensed and require additional clinical consideration.
Understanding these differences is essential for anyone seeking reliable information.
In this guide, we explain:
- What medical cannabis is
- How THC and CBD differ
- The types of cannabis-based medicines available
- What current clinical evidence tells us
- How UK prescribing and eligibility work
- Potential risks and safety considerations
- The role of pharmacies in supporting patients
Our aim is to provide clear, balanced information to help patients understand this area of healthcare.
What Is Medical Cannabis?
Medical cannabis is a broad term used to describe cannabis-based products intended for medicinal purposes.
These products may contain compounds known as cannabinoids, which occur naturally in the cannabis plant.
Two of the best-known cannabinoids are:
- Tetrahydrocannabinol (THC): A cannabinoid with psychoactive effects.
- Cannabidiol (CBD): A cannabinoid that does not produce the same characteristic intoxicating effects as THC.
However, not every product containing cannabis or CBD is legally classified as a medicine.
Cannabis-based medicinal products are subject to requirements relating to their manufacture, prescribing, distribution and supply.
Some are licensed medicines with approved indications. Others are unlicensed products that may be prescribed in particular circumstances.
When Did Medical Cannabis Become Legal in the UK?
On 1 November 2018, changes to UK controlled-drug legislation permitted certain cannabis-based products for medicinal use to be prescribed under defined circumstances.
This was an important change to the regulatory framework.
However, it did not legalise recreational cannabis or permit unrestricted access to cannabis products.
It is important to distinguish between:
Prescription cannabis-based medicines
Medicines prescribed and supplied under the applicable medical, pharmaceutical and controlled-drug requirements.
Recreational cannabis
Cannabis possessed or supplied outside lawful exemptions. Unauthorised possession and supply remain illegal.
Consumer CBD products
Products that may be sold under separate regulatory requirements, depending on their composition and intended use. These are not necessarily equivalent to prescription medicines.
The fact that a product contains cannabis, hemp or CBD does not automatically mean it is clinically effective, legally compliant or suitable for medical use.
How Does Medical Cannabis Work?
The cannabis plant contains numerous chemical compounds, including cannabinoids.
Some cannabinoids interact with a biological signalling system known as the endocannabinoid system (ECS).
The endocannabinoid system includes receptors, naturally occurring signalling molecules and enzymes.
It is involved in several physiological processes, including aspects of appetite, memory, movement and responses to pain.
Researchers continue to investigate how cannabinoids interact with this system and whether those interactions can be used safely and effectively in medical treatment.
What Is THC?
THC, or delta-9-tetrahydrocannabinol, is the principal intoxicating cannabinoid found in cannabis.
It interacts with cannabinoid receptors and can influence perception, mood, coordination and concentration.
THC-containing medicines may have specific clinical uses, but they can also cause adverse effects.
Potential effects include:
- Dizziness or drowsiness
- Reduced concentration
- Impaired coordination
- Changes in perception
- Anxiety or changes in mood
- Increased heart rate
THC exposure may also carry psychological and dependency-related risks.
The nature and likelihood of adverse effects depend on the individual, medicine, dose and circumstances of use.
What Is CBD?
CBD, or cannabidiol, is another naturally occurring cannabinoid.
Unlike THC, CBD does not produce the same characteristic intoxicating effects.
A purified prescription cannabidiol medicine has demonstrated benefits for certain severe epilepsy syndromes and is licensed for specific indications.
However, this does not mean that all CBD products have proven medical benefits.
Research into CBD for other conditions continues, but the available evidence varies and is insufficient to support many general health claims.
CBD can also interact with other medicines and may affect liver function.
Professional assessment and monitoring may therefore be necessary.
What Is the Difference Between THC and CBD?
Although THC and CBD originate from the same plant, they have different pharmacological properties, effects and safety considerations.
| THC | CBD |
| Produces intoxicating effects | Does not produce the same characteristic intoxicating effects |
| Can affect perception and coordination | Has different effects on the nervous system |
| Associated with certain psychological and impairment risks | Can cause side effects and medicine interactions |
| Has specific pharmaceutical applications | Has established applications in certain licensed epilepsy medicines |
Neither cannabinoid should be considered universally effective or suitable.
A medicine’s clinical suitability depends on the specific product, indication, dose, evidence and individual patient.
What Types of Medical Cannabis Are Available in the UK?
Cannabis-based medicinal products can be broadly divided into two categories:
- Licensed medicines
- Unlicensed medicines
Understanding the difference is important because the evidence, prescribing rules and regulatory assessments are not identical.
Licensed Cannabis-Based Medicines
Licensed medicines have received regulatory authorisation for specific indications following an assessment of quality, safety and efficacy.
Examples of medicines involving cannabinoids include:
Epidyolex (cannabidiol)
A purified cannabidiol oral solution authorised for certain severe epilepsy syndromes, subject to its licensed indications and prescribing requirements.
Sativex (nabiximols)
An oromucosal spray containing THC and CBD, licensed for symptom improvement in selected adults with moderate to severe multiple sclerosis spasticity who have not responded adequately to other treatments.
Nabilone
A synthetic cannabinoid medicine used in certain circumstances for chemotherapy-induced nausea and vomiting when other treatments have not been effective or suitable.
These medicines have different indications, precautions and prescribing requirements.
They are not interchangeable.
Unlicensed Cannabis-Based Medicinal Products
Some cannabis-based medicinal products are supplied as unlicensed medicines.
An unlicensed medicine has not undergone the same product-specific marketing-authorisation assessment as a licensed medicine.
Depending on the product and prescribing circumstances, unlicensed preparations may be available in different pharmaceutical forms, including:
- Oral solutions and oils
- Capsules and other oral preparations
- Cannabis flower intended for use with an appropriate vaporisation device
The existence of different formulations does not mean that one form is necessarily more suitable or effective than another.
Prescribing decisions must take account of clinical need, available evidence, potential risks, appropriate alternatives and relevant legal requirements.
Patients should only use prescribed medicines according to the instructions provided by their healthcare professionals.
What Does the Clinical Evidence Say About Medical Cannabis?
Scientific research into cannabis-based medicines continues to develop.
However, the strength of evidence differs considerably between individual products and medical conditions.
For some licensed medicines, clinical trials have demonstrated benefits in specific circumstances.
For many other proposed uses, the evidence remains limited, mixed or insufficient to support routine prescribing.
This distinction is particularly important when interpreting general claims about medical cannabis.
Medical Cannabis and Severe Epilepsy
A purified cannabidiol medicine is licensed for use in certain severe epilepsy syndromes, subject to the relevant indications.
This evidence relates to the specific authorised medicine and the clinical circumstances in which it has been studied.
It should not be interpreted as evidence that all cannabis or CBD products are effective for epilepsy.
Medical Cannabis and Multiple Sclerosis
Nabiximols, an oromucosal spray containing THC and CBD, has an established licensed role for selected adults with multiple sclerosis-related spasticity.
NICE provides recommendations on when a trial may be appropriate and the response required for treatment to continue.
The recommendations do not apply automatically to other cannabis-based products.
Medical Cannabis and Chemotherapy-Related Nausea
Nabilone may be considered for adults experiencing persistent chemotherapy-induced nausea and vomiting when optimised conventional anti-sickness treatment has not been sufficient.
Its use requires consideration of potential adverse effects and interactions.
What About Chronic Pain?
Cannabis-based medicines have been investigated for various types of pain.
However, the clinical evidence has important limitations.
NICE guideline NG144 recommends against offering several cannabis-based medicines for managing chronic pain in adults.
It also recommends that CBD should not be offered for chronic pain outside a clinical trial.
Some private specialists may assess individual cases involving unlicensed medicines, but this does not establish that those products are routinely recommended, proven effective or suitable for everyone.
Prescribing decisions should involve careful assessment of the available evidence, clinical circumstances, treatment alternatives and potential harms.
What About Other Medical Conditions?
Research continues into cannabinoids and a range of medical conditions.
However, study findings vary considerably.
Differences in the cannabinoid preparation, formulation, dose, patient population and study design can make results difficult to compare.
Evidence relating to one product cannot automatically be applied to another.
Patients should be cautious about claims that cannabis-based medicines can successfully treat numerous unrelated conditions.
For further information, read our guide: What Conditions Can Medical Cannabis Help With?.
Is Medical Cannabis Legal in the UK?
Certain cannabis-based products for medicinal use can legally be prescribed and supplied in the UK when the applicable requirements are satisfied.
The legal framework distinguishes prescription medicines from recreational cannabis and consumer CBD products.
For unlicensed cannabis-based medicinal products subject to the specialist-prescribing restrictions, the initial prescribing decision must be made by a doctor on the General Medical Council’s Specialist Register.
Specific requirements also apply to subsequent prescribing arrangements.
Licensed medicines are subject to their own prescribing requirements and relevant clinical guidance.
All prescribing must take place within applicable legal and professional standards.
Who Can Be Prescribed Medical Cannabis?
There is no universal checklist that guarantees eligibility for a cannabis-based medicine.
A clinical assessment must consider factors such as:
- The patient’s diagnosis and medical history
- Previous and current treatments
- Available clinical evidence
- Potential medicine interactions
- Relevant physical and mental health considerations
- Treatment alternatives
- Potential benefits, uncertainties and risks
The prescribing clinician must determine whether a particular medicine is clinically appropriate.
An initial questionnaire or eligibility enquiry is not a diagnosis and does not guarantee prescribing.
Is Medical Cannabis Available on the NHS?
Yes, but NHS prescribing is limited.
Certain cannabis-based medicines may be considered for patients with specific clinical circumstances, including particular severe epilepsy syndromes, multiple sclerosis spasticity and chemotherapy-related nausea and vomiting.
The precise recommendations depend on the medicine and relevant clinical criteria.
Not every patient with these conditions will be suitable for treatment.
Are Private Prescriptions Available?
Private specialist healthcare providers may assess patients and consider prescribing in accordance with the relevant rules.
The availability of a private consultation does not mean that a prescription will be issued.
Clinical decisions must remain independent and based on an individual assessment.
For more information, read Medical Cannabis in the UK: Who Qualifies and How to Access It.
How Does the Private Prescription Process Work?
The exact process may differ between healthcare providers, but there are several common stages.
Step 1 — Initial Enquiry
Patients may begin by providing information about their medical history, condition and previous treatment.
This information can help identify appropriate next steps.
An initial enquiry does not establish treatment suitability.
Step 2 — Specialist Consultation
An appropriately qualified clinician undertakes a clinical assessment.
This may involve reviewing:
- Medical records and diagnosis
- Previous treatments
- Current medicines
- Relevant risk factors
- Available clinical evidence
- Alternative treatment options
Step 3 — Prescribing Decision
If a medicine is considered clinically appropriate, the prescribing professional may issue a prescription in accordance with applicable requirements.
A prescription is never guaranteed.
Step 4 — Pharmacy Dispensing
The prescription is received by an appropriate pharmacy.
The pharmacy carries out the necessary professional and legal checks before dispensing.
Supply is also subject to relevant requirements and product availability.
Step 5 — Ongoing Clinical Review
Where treatment is prescribed, appropriate monitoring and review are essential.
The prescribing clinician assesses outcomes, potential adverse effects and whether treatment should continue or change.
Is Medical Cannabis Safe?
Cannabis-based medicinal products can cause side effects and may interact with other medicines.
The nature of these risks varies depending on the product, dose and patient.
Potential adverse effects include:
- Drowsiness or fatigue
- Dizziness
- Nausea or gastrointestinal symptoms
- Impaired concentration
- Changes in mood or behaviour
- Reduced coordination
- Psychological adverse effects associated with THC-containing products
Some medicines may also require particular monitoring, including liver-function assessment or checks for interactions.
Who May Need Additional Precautions?
Certain patients may require particular caution, including people with relevant medical histories, those taking interacting medicines and people who are pregnant or breastfeeding.
A healthcare professional should consider these circumstances before prescribing.
Can Medical Cannabis Interact With Other Medicines?
Yes.
THC, CBD and other components of cannabis-based medicines may interact with prescribed or non-prescribed medicines.
Patients should provide an accurate list of their medicines and supplements to their healthcare team.
Can You Drive While Taking Medical Cannabis?
Some cannabis-based medicines can impair driving ability.
Having a valid prescription does not make it safe or lawful to drive while impaired.
Patients should discuss driving and other safety-sensitive activities with their prescribing clinician and pharmacist.
What Should You Do If You Experience Side Effects?
Contact your healthcare team for advice.
Suspected adverse drug reactions can also be reported through the MHRA Yellow Card scheme.
Seek urgent medical attention for severe or potentially life-threatening symptoms.
Medical Cannabis vs CBD Supplements: What Is the Difference?
Prescription cannabis-based medicines and consumer CBD products are regulated differently.
Prescription medicines are subject to specific pharmaceutical, prescribing and supply requirements.
Consumer CBD products may fall under other regulatory frameworks, depending on their composition and intended use.
Differences may include:
- Manufacturing and quality standards
- Product composition and concentration
- Clinical evidence
- Regulatory authorisation
- Intended use
- Professional supervision and monitoring
A consumer CBD product should not be assumed to have the same clinical effects or quality standards as a prescription medicine.
Patients should inform their healthcare professionals about supplements they use because interactions may occur.
How Does IYOS Pharmacy Support Patients?
IYOS Pharmacy is a General Pharmaceutical Council (GPhC)-registered pharmacy providing private prescription dispensing and related pharmacy services.
We work alongside independent specialist clinics to help patients navigate the practical aspects of private prescription care.
Our approach combines professional pharmacy standards with clear communication and ongoing patient support.
Professional Prescription Dispensing
Our pharmacy team undertakes the necessary professional and legal checks before dispensing valid prescriptions.
Coordination With Specialist Clinics
We work with independent prescribing providers where appropriate to support prescription processing and continuity of care.
Secure and Discreet Delivery
Once prescriptions have been appropriately checked and dispensed, we arrange secure and discreet delivery in accordance with the relevant requirements.
Prescription Management
Our team can assist patients with dispensing arrangements, prescription enquiries and coordination of renewal requests where appropriate.
Ongoing Pharmacy Support
We provide professional pharmacy guidance about prescribed medicines and help patients understand the practical steps involved in ongoing care.
All clinical assessments, treatment decisions and prescribing remain the responsibility of appropriately qualified healthcare professionals.
At IYOS Pharmacy, our aim is to make professional pharmacy care clear, supportive and convenient throughout the patient journey.
Frequently Asked Questions About Medical Cannabis
1. What is medical cannabis?
Medical cannabis refers to cannabis-based products used for medicinal purposes. In the UK, certain cannabis-based medicines can be prescribed under strict medical and regulatory requirements.
2. Is medical cannabis legal in the UK?
Yes. Certain cannabis-based medicinal products can legally be prescribed and supplied when applicable requirements are met. Recreational cannabis remains illegal.
3. Who can prescribe medical cannabis?
For unlicensed cannabis-based medicinal products subject to specialist-prescribing restrictions, the initial prescribing decision must be made by a doctor on the GMC Specialist Register. Different requirements may apply to licensed medicines and subsequent prescriptions.
4. Is medical cannabis available through the NHS?
Yes, but access is limited to particular medicines and clinical circumstances. Most patients will not be eligible for an NHS prescription.
5. Is medical cannabis the same as CBD oil?
No. Consumer CBD products and prescription cannabis-based medicines have different regulatory requirements, formulations and evidence bases.
6. Does medical cannabis work for everyone?
No. The available evidence varies by medicine and condition, and treatment responses differ between individuals. Suitability requires a clinical assessment.
7. Can medical cannabis cause side effects?
Yes. Side effects may include dizziness, drowsiness, gastrointestinal symptoms, impaired coordination and changes in mood. Risks depend on the medicine and patient.
8. Can medical cannabis interact with other medicines?
Yes. Cannabinoids can interact with other medicines. Patients should discuss their current prescriptions and supplements with their healthcare professionals.
9. Can I use my preferred pharmacy for a private prescription?
Patients can enquire about using their preferred pharmacy, subject to prescription validity, applicable supply requirements and the pharmacy’s ability to provide the prescribed medicine.
10. Does IYOS Pharmacy prescribe medical cannabis?
IYOS Pharmacy provides dispensing and related pharmacy services. Independent specialist clinicians undertake clinical assessments and prescribing decisions.
Key Takeaways: Understanding Medical Cannabis
Medical cannabis is a regulated area of healthcare, and understanding the distinction between established evidence, emerging research and unsupported claims is important.
The main points to remember are:
- Certain cannabis-based medicinal products can legally be prescribed in the UK.
- Licensed medicines have authorised indications, while unlicensed medicines require additional professional consideration.
- THC and CBD have different effects and safety considerations.
- Clinical evidence varies considerably between medicines and conditions.
- Specialist prescribing restrictions apply to certain unlicensed cannabis-based medicinal products.
- Cannabis-based medicines can cause adverse effects and interactions.
- Appropriate assessment and clinical monitoring are essential.
- IYOS Pharmacy provides professional dispensing, prescription coordination and pharmacy support.
For individual medical advice, patients should consult an appropriately qualified healthcare professional.
Further Reading and Official Sources
This guide draws on authoritative UK healthcare and medicines guidance.
1. NHS — Medical Cannabis (Cannabis Oils)
Information about prescription access, patient safety and potential adverse effects.
2. NICE — Cannabis-Based Medicinal Products (NG144)
Clinical recommendations relating to cannabis-based medicines, including chronic pain, multiple sclerosis spasticity and chemotherapy-induced nausea and vomiting.
3. NICE — Detailed Prescribing Recommendations
Specific recommendations concerning the use of cannabis-based medicinal products.
4. General Medical Council — Good Practice in Prescribing and Managing Medicines and Devices
Professional standards covering prescribing decisions, patient safety and the responsibilities of prescribers.
5. MHRA — Yellow Card Scheme
The UK system for reporting suspected adverse drug reactions.
Explore More Medical Cannabis Guides
Continue learning with IYOS Pharmacy’s patient education resources.
Medical Cannabis in the UK: Who Qualifies and How to Access It
Learn about the UK prescription framework, specialist assessments and how private prescription processes work.
Read the eligibility and access guide
What Conditions Can Medical Cannabis Help With?
Understand the difference between licensed medical indications, current clinical evidence and other areas of ongoing research.
Here to Help, Every Step of the Way
At IYOS Pharmacy, we believe patients should have access to clear, reliable information and professional pharmacy support.
Whether you’re trying to understand the private prescription process or already receive care through an independent specialist clinic, our pharmacy team can help with dispensing enquiries and practical questions about our services.
Medical Disclaimer
This article is intended for general educational purposes and does not constitute medical advice, diagnosis or a recommendation for any particular medicine or treatment.
Cannabis-based medicinal products are subject to legal, regulatory and professional requirements. Treatment suitability and prescribing decisions must be determined by appropriately qualified healthcare professionals following an individual clinical assessment.
Patients should not start, stop or change prescribed medicines without appropriate professional advice.
Editorial information
Content author: IYOS Pharmacy Editorial Team
Editorial review date: 2 November 2026
IYOS Pharmacy aims to provide accurate, balanced and accessible patient education using recognised clinical guidance and authoritative healthcare sources.
