Medical cannabis has been made legal in the UK. This means that in some circumstances, specialist doctors may prescribe it to treat epilepsy. On this page, we answer some of the most frequently asked questions about medical cannabis for epilepsy.
What is medical cannabis?
'Medical cannabis' is a broad term for any sort of cannabis-based medicine used to relieve symptoms. These medicines are all based on a part, or parts of the cannabis plant.
The cannabis plant contains hundreds of natural chemicals. When looking at medical cannabis, the two most important are cannabidiol (CBD) and tetrahydrocannabinol (THC).
CBD does not have the mood-altering effects often associated with cannabis. There has been a lot of research into the potential of CBD as an epilepsy treatment.
THC is the part of the cannabis plant that makes people feel ‘high’. More research is needed to find out if products containing THC are safe or effective for treating epilepsy.
What types of medical cannabis are available to treat epilepsy?
At the moment, there are no forms of medical cannabis licensed to treat epilepsy in the UK. A cannabis-based medicine called Epidiolex, containing CBD, is currently going through the licensing process. In the meantime, although it is unlicensed, specialists may prescribe it in rare circumstances.
There have been a small number of cases of children with severe epilepsy being prescribed unlicensed cannabis oil containing CBD and THC. It’s not clear at the moment how frequently this will be prescribed by specialists, but it’s likely to only be in very rare circumstances, where CBD alone hasn't helped. This is because there is no clear evidence that THC is of additional benefit. And there is concern about its effect on brain development and mental health, particularly in children and young adults.
How can I get medical cannabis for my child?
To see if medical cannabis might be helpful for your child, speak to their epilepsy specialist.
The British Paediatric Neurology Association (BPNA) recommends that medical cannabis should be used as a ‘treatment of last resort’ for children who:
- Have tried all the available licensed medicines for their type of epilepsy without success
- Are either not suitable for the ketogenic diet, or have tried the ketogenic diet and it didn’t work
- Are not suitable for epilepsy surgery
If a child meets all these criteria, the BPNA recommends prescribing the CBD-based medicine Epidiolex. The BPNA does not recommend prescribing cannabis oil or any form of medical cannabis other than Epidiolex. However, these are only recommendations, and it will be up to your child’s specialist to decide whether to prescribe medical cannabis and in what form.
The BPNA says only consultant paediatric neurologists should prescribe medical cannabis.
Even if a paediatric neurologist recommends medical cannabis for your child, the decision must be approved by the hospital. The NHS in your local area will also need to agree to pay for it.
I’m an adult with epilepsy. Can I get a prescription for medical cannabis?
It’s likely that medical cannabis will only be considered as a treatment option for a very small number of adults. Specialists are likely to only recommend medical cannabis for adults with very severe epilepsy that started in childhood. And only when all other treatments have failed.
The Association of British Neurologists (ABN) has published guidelines on the use of cannabis-based products in neurology. It says specialists should only prescribe medical cannabis for adults diagnosed with Dravet syndrome or Lennox-Gastaut syndrome. These are both rare and severe forms of epilepsy.
If an epilepsy specialist recommends medical cannabis for you, the decision must be approved by the hospital. The NHS in your local area will also need to agree to pay for it.
Can my GP prescribe medical cannabis?
GPs cannot prescribe medical cannabis. It can only be prescribed by specialist doctors.
I’ve seen CBD products online and in my local health food shop. Can I use them to treat my epilepsy?
CBD products sold online and in health food shops are not licensed as medicines. Companies selling these products are not allowed to make any claims about their ability to treat any condition. It is extremely unlikely that they will be made to the same standard as medicines. And you cannot guarantee what their quality will be.
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 or your child’s existing epilepsy medicines work. You should not stop taking your epilepsy medicine unless your epilepsy specialist advises you to, as stopping could cause you to have more frequent or severe seizures.
What evidence is there that medical cannabis can help people with epilepsy?
There has been a lot of research into medical cannabis 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 150) would become seizure free.
Patients have reported side-effects when taking CBD. Some of those reported were drowsiness, diarrhoea, reduced appetite and fatigue. Side-effects happen in around 1 in 3 people taking CBD.
There’s some evidence that when CBD is taken alongside epilepsy medicines, the levels of the epilepsy 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 medical cannabis as an ‘add-on’ therapy for people who are already taking a number of epilepsy medicines. This means we don’t know if medical cannabis works when taken on its own.
There haven’t been any studies comparing medical cannabis with other medicines already licensed for treating epilepsy. So we don’t know if medical cannabis is more or less effective than other epilepsy treatments. Neither do we know if it is 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 medical cannabis is 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.
Where can I read more about medical cannabis and epilepsy?
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 her contribution.
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 Epilepsy Action's information quality standards.
- Updated November 2018To be reviewed November 2021