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Cannabis-based treatments for epilepsy in the UK

Cannabis-based treatments for epilepsy have generated a lot of interest in recent years. On this page we answer some of the most frequently asked questions about cannabis-based treatments and epilepsy.

What are cannabis-based treatments?

Cannabis contains hundreds of chemicals that occur naturally in the plant. The two most important are tetrahydrocannibidiol (THC) and cannabidiol (CBD). THC is the part that makes people feel ‘high’ but can also cause negative effects such as anxiety and paranoia. CBD is not connected with the mood-altering effects of cannabis, and has been the subject of a lot of research into its potential as an epilepsy treatment.

The term cannabis-based treatments covers a number of different products. Some contain CBD only, while others contain CBD and THC.

Cannabis oil containing CBD and THC: There have been recent cases of parents in the UK trying to access cannabis oil containing CBD and THC for their children with severe epilepsy. Cannabis oil is not currently licensed as a medicine in the UK, but following a recent Home Office announcement may be available for specialists to prescribe from autumn 2018.

Medicine based on CBD: Epidiolex is a medicine made from CBD developed by GW Pharmaceuticals. It doesn’t have a licence for use in the UK but recently got approval in the US for use in two rare epilepsy syndromes. A decision is expected from the European Medicines Agency on the use of Epidiolex in the UK and Europe early in 2019.

CBD products sold in health food shops: These contain no, or only trace amounts of, THC. They can legally be sold in the UK, and you may see them sold online as well as in health food shops. They are not currently licensed as medicines.

What evidence is there that cannabis-based treatments can help people with epilepsy?

There has been a lot of research into cannabis-based treatments for epilepsy in recent years. Most studies have focused on CBD, and most have involved children with rare and serious epilepsy syndromes, who are already taking a number of epilepsy medicines.

What we know:

Studies suggest that CBD may be an effective treatment for children with some types of hard-to-treat epilepsy. To assess how effective an epilepsy treatment is, researchers often look at how many people have a 50% or greater reduction in seizures. A recent evidence review found that one in every 8 people taking CBD would have a 50% or greater reduction in seizures. A much smaller number (less than 1 in 100) would become seizure free.

Patients have reported side-effects when taking CBD and other cannabis-based treatments. Some of those reported were drowsiness, diarrhoea, reduced appetite and fatigue. Side-effects occur in around 1 in 3 people taking CBD.

There’s some evidence that when CBD is taken alongside epilepsy medicines, the levels of those medicines in the blood may be affected. With some medicines this can have potentially dangerous consequences. For example, people taking CBD with clobazam may have increased sedation, and people taking CBD with sodium valproate may have altered liver function.

What we don’t know:

Most studies have looked at cannabis-based treatments as an ‘add-on’ therapy for people who are already taking a number of epilepsy medicines. This means we don’t know if cannabis-based treatments work when taken on their own.

There haven’t been any studies comparing cannabis-based treatments with other medicines already licensed for treating epilepsy. So we don’t know if cannabis-based treatments are more or less effective than other epilepsy treatments. Neither do we know if they are more or less safe than other epilepsy treatments.

There’s also not enough evidence yet to say if products containing both CBD and THC are safe or effective. Neither is there evidence to say if the THC component is of any additional benefit. We do know, however, that THC does have a risk of additional side-effects.

As most studies have focused on children with specific types of hard-to-treat epilepsy, there’s not enough evidence to say if cannabis-based treatments are useful for other people with epilepsy.

Most studies have used highly-regulated, ‘pharmaceutical grade’ CBD under medical supervision. We don’t know if unregulated CBD products (for example those available in health food shops) are safe or effective.

How can I get cannabis-based treatment for myself or my child?

The options for getting cannabis-based treatment prescribed in the UK are extremely limited. And they vary depending on the type of treatment.

Cannabis oil containing CBD and THC

If your specialist thinks you or your child need cannabis oil containing CBD and THC they can apply to an expert panel set up by the Home Office. The panel will only accept applications from specialist doctors, so you can’t apply to the panel yourself.

Your specialist will need to show the panel that you or your child have an exceptional clinical need for cannabis oil. This is only likely to apply to people who are having very frequent seizures despite trying a number of other epilepsy medicines.

From autumn 2018 specialists will be able to legally prescribe ‘cannabis derived medicinal products’. It’s likely that when this happens specialists will be able to prescribe some forms of cannabis oil without having to apply to the expert panel. However, specialists are still unlikely to recommend cannabis oil for anyone who hasn’t already tried existing epilepsy medicines.


The CBD-based medicine Epidiolex may become available for people with certain rare epilepsy syndromes in the UK in 2019. In time, the company making Epidiolex may conduct more research to see if it’s effective for other types of epilepsy. Your epilepsy specialist will be able to tell you if they think Epidiolex might be a suitable treatment. They can also tell you about any research studies involving Epidiolex that you or your child could take part in.

CBD products sold in health food shops and online

Products containing CBD are available to buy legally from online suppliers and on the high street. These products are not currently licensed as medicines, so they may not be produced to the same standard as medicines. There’s also no information about what dose someone would need to take to control or reduce seizures.

If you do choose to use CBD products for yourself or your child it’s important to let your epilepsy specialist know. This is because the CBD product could affect the way your existing epilepsy medicines work. You should not stop taking your epilepsy medicine unless your specialist advises you to, as stopping could cause you to have more frequent or severe seizures.

Where can I read more about cannabis-based treatments and epilepsy?

Read Epilepsy Action’s position statements on cannabis-based treatments
Read the Home Office announcement on cannabis-based treatments

If you would like to see this information with references, visit the Advice and Information references section of our website or contact our Epilepsy Action freephone helpline on 0808 800 5050.

Event Date: 
Friday 3 August 2018 (All day)

Epilepsy Action would like to thank Professor Hannah Cock, professor of epilepsy and medical education and consultant neurologist at St George’s University Hospitals, for reviewing this information.

Professor Cock has declared an interest in the subject of cannabis-based treatments and epilepsy. Epilepsy Action does not believe this interest has influenced the content of this information or Professor Cock’s impartiality as an adviser. For further details please contact the Epilepsy Action Helpline.

This information has been produced under the terms of The Information Standard.

  • Updated August 2018
    To be reviewed August 2021

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