Medical cannabis in the UK

What is medical cannabis?

‘Medical cannabis’ is a term used to describe a range of cannabis-based medicines.

The cannabis plant contains hundreds of natural chemicals. The two most commonly-known chemicals are cannabidiol (CBD) and tetrahydrocannabinol (THC).

CBD does not have the mood-altering effects often associated with cannabis. There has been a lot of scientific research into CBD as an epilepsy treatment.

THC is the part of the cannabis plant that makes people feel ‘high’. Some small studies have shown that small amounts of THC may be effective. But we need more research.

Are there any cannabis-based medicines for epilepsy?

Cannabidiol is the only cannabis-based medicine approved for treating epilepsy in the UK. It is a highly purified liquid containing CBD. It contains trace amounts of THC, but not enough to affect the brain or cause a ‘high’.

The brand name for cannabidiol is Epidyolex. This is only available on the NHS for some adults and children with certain types of epilepsy. It is not suitable for children under 2 years old.

The NICE (National Institute for Health and Care Excellence) guidelines set out how medicines can be prescribed in the NHS. Private doctors on the General Medical Council’s specialist register are also legally able to prescribe medical cannabis. They follow the same guidelines.

NICE recommend Epidyolex if you, or a child over 2 years old has: 

• Dravet syndrome or 

• Lennox-Gastaut syndrome or 

• Tuberous sclerosis complex (TSC)

The NICE recommendations apply to England, Northern Ireland and Wales. The Scottish Medicines Consortium also recommends Epidyolex for people with the above syndromes.

Epidyolex is only recommend if you have already tried 2 or more epilepsy medicines to control your seizures. 

Your specialist should check that Epidyolex is controlling your seizures regularly. They should check how often you are having seizures every 6 months. Your treatment will stop if your seizures do not reduce by at least 30%. This is compared to the number of seizures you had in the 6 months before starting treatment. 

You will need to take Epidyolex with Clobazam if you have Dravet syndrome or Lennox-Gastaut syndrome.

Talking to your specialist

Before prescribing medical cannabis, your specialist will talk to you about: 

• If you have used cannabis before 

• Any history of substance abuse 

• Your mental health 

• Your medical history 

• How medical cannabis could interact with your other medicines 

• If you are pregnant or breastfeeding

Your specialist should talk to you about the pros and cons of taking Epidylex. This will help you make an informed decision about your care.  

You should not use any other cannabis products while taking Epidyolex. 

Contact our Campaigns team if your specialist won’t prescribe Epidyolex and you do not agree. Email campaigns@epilepsy.org.uk     

Medical cannabis and pregnancy

You should not take Epidyolex while you are pregnant unless the benefits outweigh the potential risks. Talk to your epilepsy specialist if you are pregnant or thinking about getting pregnant.

Does Epidyolex cause side effects?

Like all medicines, Epidyolex can cause side effects. The most common side effects may happen in more than 1 in 10 people. These include:

• Feeling drowsy or sleepy
• Diarrhoea
• Feeling less hungry
• Fever
• Being sick (vomiting)

You can get more information about side effects from the Epidyolex patient leaflet.

Does Epidyolex interact with other epilepsy medicines?

Epidyolex can affect how well other epilepsy medicines work. This includes lorazepam, phenytoin, and valproate.

Epidyolex can also affect how well other medicines work. For example, medicines used to treat acid reflux, such as omeprazole.

Talk to your specialist or pharmacist before starting or stopping other medicines.

You can find a full list of interactions here. 

Can people with other types of epilepsy get a prescription for Epidyolex?

There is some evidence that CBD may be effective for other types of epilepsy. For example, Doose syndrome and Sturge-Webber syndrome. This evidence is not good enough for NICE to recommend it.

But specialists may still prescribe it for people with other types of epilepsy. This would be on a case-by-case basis and only in exceptional circumstances. For example, if other treatments have not worked.

Research into CBD medicines is ongoing. NICE has called for more research into its use for severe, treatment (drug) resistant-epilepsy. This means some people might be able to access Epidyolex by taking part in clinical trials. Your specialist will be able to tell you if there are any clinical trials you could take part in.

RESCAS is the Refractory Epilepsy Specialist Clinical Advisory Service. This is an advice service for specialists who are looking after patients under 18 years old. You can discuss a referral to this service with your child’s specialist. They may be able help if your child’s epilepsy is complex and isn’t responding to treatment.

Can I use medical cannabis with cannabidiol (CBD) and tetrahydrocannabinol (THC)?

NICE have only made recommendations about prescribing medicines containing CBD for epilepsy. They have not yet made any recommendations about prescribing medicines containing CBD and THC for everyone with severe treatment-resistant epilepsy. Evidence suggests these medicines may be effective. But the research so far is limited and of low quality.

But this does not mean that healthcare professionals cannot prescribe unlicensed cannabis-based medicines. NICE says that specialists can prescribe unlicensed medicines on a case-by-case basis. Your healthcare professional may suggest this if they think the benefit outweighs the risk.

A small number of children in the UK are treated with unlicensed cannabis oil containing CBD and THC. These are children with severe epilepsy.

The reasons your specialist may prescribe unlicensed medicines with THC include:

• They believe the medicine would work well for you
• They have thought about all the medical evidence available and believe it is safe and effective

NICE has called for more research into medicines containing CBD and THC. This means some people might be able to access these medicines by taking part in clinical trials. Your specialist will be able to tell you if there are any clinical trials you could take part in.

A large medical study into using CBD and THC will start in 2025. Researchers from University College London and Great Ormond Street Hospital will look at how CBD and THC can help adults and children with treatment-resistant epilepsy. Read more about this research.

Can I use CBD products found online and in health food shops to treat my epilepsy?  

You can buy CBD products in health shops. This includes CBD oils and food supplements. But there is no guarantee that these are good quality products.

These products tend to only contain very small amounts of CBD, so it’s not clear what effect they would have.

Many cannabis-based products are also available to buy online. But their quality and content is not known. They may be illegal in the UK and potentially dangerous.

Can CBD products trigger seizures? 

Research has also shown that CBD can affect how well epilepsy medicines work.

It’s important to tell your epilepsy specialist if you or your child use CBD products that have not been prescribed. This is because the CBD product could affect how the epilepsy medicines work to control your seizures.

Do not stop taking your epilepsy medicine without speaking to your specialist. Stopping suddenly could cause more frequent or severe seizures.

Can I use non-medical/recreational cannabis to treat epilepsy?

Cannabis bought illegally off the street can be dangerous. It can contain high levels of THC. 

We strongly advise that you do not smoke, eat or vape recreational, illegally-sourced cannabis to treat epilepsy. There is not enough scientific evidence to know how it effects epilepsy. We do not know if it makes symptoms better or worse. THC can also increase the risk of seizures. 

We do not know the quality, ingredients and strength of cannabis bought illegally. You could be smoking, eating or vaping chemicals from unknown substances. This includes pesticides used when growing the cannabis.

Non-prescribed cannabis can make some existing mental health symptoms worse. It has also been linked with the possible development of mental health issues. These mental health problems are seen more clearly in people aged 10-19 than in adults. Using a lot of recreational cannabis can affect their brain development.

Cannabis can also cause sleep problems, which is a seizure trigger for some people.

Mixing cannabis with tobacco increases the risk of heart problems and various cancers. 

FRANK has more information about cannabis.

What is Epilepsy Action doing about medical cannabis for epilepsy?

Epilepsy Action is campaigning for research into products that contain THC and CBD.

We need research into the benefits of Epidyolex for other types of epilepsy. There are barriers preventing people with epilepsy accessing cannabis-based medicines in the NHS. We want to remove these barriers for people who need it. Particularly people with severe and treatment resistant epilepsies.

Read our campaigns page about epilepsy and cannabis-based medicines.

Thanks to Medcan Family Foundation for reviewing this information.