Specialist hospital doctors can prescribe or recommend cannabis-based products for treatment. The products can be used when the specialist identifies a clinical need for a person and other treatments are not suitable or have not helped.
About medicinal cannabis products
‘Medicinal cannabis’ is a broad term for any sort of cannabis-based product used to relieve symptoms.
Many of these products are available to buy online without a prescription, but their quality and content cannot be guaranteed. These products could be illegal and potentially dangerous.
Some products that might claim to be medicinal cannabis, such as ‘CBD’ oil or hemp oil, are available to buy as food supplements from health stores and other outlets, but there is no guarantee these are effective or of good quality.
Some cannabis-based products are available on prescription as medicinal cannabis. These are only likely to benefit a very small number of patients.
Prescriptions for a medicinal cannabis product
Medicinal cannabis products are only available on a prescription written by, or recommended by, a specialist hospital doctor.
This is because there is currently limited scientific evidence medicinal cannabis is safe and effective. It is also because there are relatively few licensed products available that have undergone the normal strict testing for medicines. This testing means that medicines are safe, of good quality, and are effective.
A hospital specialist might consider prescribing a medicinal cannabis product for you or your child if:
- your child has one of the rare forms of epilepsy that might be helped by medical cannabis
- you have spasticity from Multiple Sclerosis (MS) and treatments for this are not helping
- you have vomiting or feel sick from chemotherapy and anti-sickness treatments aren't helping
Medicinal cannabis will generally only be considered when other treatments were not suitable or had not helped. The specialist will discuss with you the most suitable treatment option.
If the above does not apply it is unlikely your GP will refer you or your child for medicinal cannabis.
How medicinal cannabis products might help
Epidyolex for children and adults with epilepsy
Epidyolex is a highly purified liquid containing CBD (cannabidiol).
CBD is a chemical substance found in cannabis that has medical benefits.
It will not get you high, because it does not contain THC (tetrahydrocannabinol), the chemical in cannabis that makes you high.
Epidyolex can be prescribed for patients with Lennox-Gastaut syndrome and Dravet syndrome (both rare forms of epilepsy).
Nabilone for chemotherapy patients
Many people having chemotherapy will have periods where they feel sick or vomit.
Nabilone can be prescribed by a specialist to help relieve these symptoms, but only when other treatments have not helped or are not suitable.
Nabilone is a medicine, taken as a capsule, which has been developed to act in a similar way to THC (the chemical in cannabis that makes you high). You may have heard it described as a "manmade form of cannabis".
Nabiximols (Sativex) for multiple sclerosis (MS)
Nabiximols (Sativex) is a cannabis-based medicine that is sprayed into the mouth.
It is licensed in the UK for people with MS-related muscle spasticity that has not got better with other treatments.
There is some evidence medical cannabis can help certain types of pain, though this evidence is not yet strong enough to recommend it for pain relief.
Researchers are currently investigating other possible uses of medicinal cannabis.
Products available to buy
Some cannabis-based products are available to buy over the internet without a prescription.
It's likely most of these products – even those called "CBD oils" – will be illegal to possess or supply. There's a good chance they will contain THC, and may not be safe to use.
Health stores sell certain types of "pure CBD". However, there's no guarantee these products will be of good quality.
They tend to only contain very small amounts of CBD, so it's not clear what effect they would have.
Is medicinal cannabis safe
The risks of using cannabis products containing THC (the chemical that gets you high) are not currently known. That is why clinical trials are needed before they can be licensed for use.
"Pure" products that only contain CBD, such as Epidyolex, do not carry these unknown risks linked with THC.
But in reality, most products will contain a certain amount of THC.
The main risks of THC cannabis products are:
- psychosis – there is evidence that regular cannabis use increases your risk of developing a psychotic illness such as schizophrenia
- dependency on the medicine – although scientists believe this risk is probably small when its use is controlled and monitored by a specialist doctor
Generally, the more THC the product contains, the greater these risks are.
Cannabis bought illegally off the street, where the quality, ingredients and strength are not known, is the most dangerous form to use.
Side effects of medicinal cannabis
After taking medicinal cannabis, it is possible side effects can develop. These include:
- decreased appetite
- feeling sick
- greater weakness
- a behavioural or mood change
- feeling very tired
- feeling high
- suicidal thoughts or hallucinations
If you experience any side effects from medicinal cannabis, report these to your medical team. You can also report them through the Yellow Card Scheme.
CBD can affect how other drugs work. If you are taking a CBD drug along with other medication, always discuss possible interactions with your specialist.
CBD can also affect how your liver works, so doctors would need to monitor you regularly.
Laws on cannabis
Cannabis is a Class-B drug in the UK.
It is illegal to:
- possess or supply cannabis-based products for medicinal use without a prescription
- produce or supply cannabis-based products that are not for medicinal use
- smoke cannabis, or cannabis-based products for medicinal use