Cannabis, CBD oil and cancer
Cannabis is a plant and a class B drug. It affects people differently. It can make you feel relaxed and chilled but it can also make you feel sick, affect your memory and make you feel lethargic. CBD oil is a chemical found in cannabis.
- Cannabis has been used for centuries recreationally and as a medicine.
- It is illegal to possess or supply cannabis as it is a class B drug.
- Research is looking at the substances in cannabis to see if it might help treat cancer.
- There are anti sickness medicines that contain man-made substances of cannabis.
What are cannabis and cannabinoids?
Cannabis is a plant. It is known by many names including marijuana, weed, hemp, grass, pot, dope, ganja and hash.
The plant produces a resin that contains a number of substances or chemicals. These are called cannabinoids. Cannabinoids can have medicinal effects on the body.
The main cannabinoids are:
- Delta-9-tetrahydrocannabinol (THC)
- Cannabidiol (CBD)
THC is a psychoactive substance that can create a ‘high’ feeling. It can affect how your brain works, changing your mood and how you feel.
CBD is a cannabinoid that may relieve pain, lower inflammation and decrease anxiety without the psychoactive ‘high’ effect of THC.
Different types of cannabis have differing amounts of these and other chemicals in them. This means they can have different effects on the body.
Cannabis is a class B drug in the UK. This means that it is illegal to have it, sell it or buy it.
CBD oil, cannabis oil and hemp oil
There are different types of oil made from parts of the cannabis plant. Some are sold legally in health food stores as a food supplement. Other types of oil are illegal.
CBD oil comes from the flowers of the cannabis plant and does not contain the psychoactive substance THC. It can be sold in the UK as a food supplement but not as a medicine. There is no evidence to support its use as a medicine.
Cannabis oil comes from the flowers, leaves and stalks of the cannabis plant. Cannabis oil often contains high levels of the psychoactive ingredient THC. Cannabis oil is illegal in the UK.
Hemp oil comes from the seeds of a type of cannabis plant that doesn’t contain the main psychoactive ingredient THC. Hemp seed oil is used for various purposes including as a protein supplement for food, a wood varnish and an ingredient in soaps.
Why people with cancer use it
Cannabis has been used medicinally and recreationally for hundreds of years.
There has been a lot of interest into whether cannabinoids might be useful as a cancer treatment. The scientific research done so far has been laboratory research, with mixed results, so we do not know if cannabinoids can treat cancer in people.
Results have shown that different cannabinoids can:
- cause cell death
- block cell growth
- stop the development of blood vessels – needed for tumours to grow
- reduce inflammation
- reduce the ability of cancers to spread
Scientists also discovered that cannabinoids can:
- sometimes encourage cancer cells to grow
- cause damage to blood vessels
Cannabinoids have helped with sickness and pain in some people.
This means a cannabis based product used to relieve symptoms.
Some cannabis based products are available on prescription as medicinal cannabis. The following medicines are sometimes prescribed to help relieve symptoms.
Nabilone is a drug developed from cannabis. It is licensed for treating severe sickness from chemotherapy that is not controlled by other anti sickness drugs. It is a capsule that you swallow whole.
Sativex is a cannabis-based medicine. It is licensed in the UK for people with Multiple Sclerosis muscle spasticity that hasn’t improved with other treatments. Sativex is a liquid that you spray into your mouth.
Researchers are looking into Sativex as a treatment for cancer related symptoms and for certain types of cancer.
How you have it
Cannabis products can be smoked, vaporized, ingested (eating or drinking), absorbed through the skin (in a patch) or as a cream or spray.
CBD oil comes as a liquid or in capsules.
Prescription drugs such as Nabilone can cause side effects. This can include:
- increased heart rate
- blood pressure problems
- mood changes
- memory problems
Cannabis that contains high levels of THC can cause panic attacks, hallucinations and paranoia.
There are also many cannabis based products available online without a prescription. The quality of these products can vary. It is impossible to know what substances they might contain. They could potentially be harmful to your health and may be illegal.
Research into cannabinoids and cancer
We need more research to know if cannabis or the chemicals in it can treat cancer.
Clinical trials need to be done in large numbers where some patients have the drug and some don’t. Then you can compare how well the treatment works.
Many of the studies done so far have been small and in the laboratory. There have been a few studies involving people with cancer.
Sativex and temozolomide for a brain tumour (glioblastoma) that has come back
In 2021, scientists reported the final results of a phase 1 study to treat people with recurrent glioblastoma (a type of brain tumour that has come back). The study looked at Sativex in combination with the chemotherapy drug temozolomide.
Researchers found that adding Sativex caused side effects, which included, vomiting, dizziness, fatigue, nausea and headache but patients found the side effects manageable.
They also observed that 83 out of 100 people (83%) were alive after one year using Sativex, compared to 44 out of 100 people (44%) taking the placebo.
However, this phase 1 study only involved 27 patients, which was too small to learn about any potential benefits of Sativex. The study wanted to find out if Sativex and temozolomide was safe to take by patients.
Researchers have now started a larger phase 2 trial called ARISTOCRAT, to find out if this treatment is effective and who might benefit from it. Speak to your specialist if you want to take part in a clinical trial.
Sativex and cancer pain
There are trials looking at whether Sativex can help with cancer pain that has not responded to other painkillers.
The results of one trial showed that Sativex did not improve pain levels. You can read the results of the trial on our clinical trials website.
Cancer and nausea and vomiting
A cannabis based medicine, Nabilone, is a treatment for nausea and vomiting.
A Cochrane review in 2015 looked at all the research available looking into cannabis based medicine as a treatment for nausea and sickness in people having chemotherapy for cancer. It reported that many of the studies were too small or not well run to be able to say how well these medicines work. They say that they may be useful if all other medicines are not working.
A drug called dexanabinol which is a man made form of a chemical similar to that found in cannabis has been trialled in a phase 1 trial. This is an early trial that tries to work out whether or not the drug works in humans, what the correct dose is and what the side effects might be. The results are not available yet. You can read about the trial on our clinical trials database.
Word of caution
Cannabis is a class B drug and illegal in the UK.
There are internet scams where people offer to sell cannabis preparations to people with cancer. There is no knowing what the ingredients are in these products and they could harm your health.
Some of these scammers trick cancer patients into buying ‘cannabis oil’ which they then never receive.
You could talk with your cancer specialist about the possibility of joining a clinical trial. Trials can give access to new drugs in a safe and monitored environment.
The science blog on our website has more information about cannabis and cancer.
Medical cannabis (and cannabis oils)
Many cannabis-based products are available to buy online, but their quality and content is not known. They may be illegal in the UK and potentially dangerous.
Some products that might claim to be medical cannabis, such as CBD oil or hemp oil, are available to buy legally as food supplements from health stores. But there’s no guarantee these are of good quality or provide any health benefits.
Specific cannabis-based products are available on prescription as medicinal cannabis. These are only likely to benefit a very small number of patients.
Can I get a prescription for medical cannabis?
Very few people in England are likely to get a prescription for medical cannabis.
Currently, it is only likely to be prescribed for the following conditions:
- children and adults with rare, severe forms of epilepsy
- adults with vomiting or nausea caused by chemotherapy
- people with muscle stiffness and spasms caused by multiple sclerosis (MS)
It would only be considered when other treatments were not suitable or had not helped.
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 by a specialist 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 to adults 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, that 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 adults 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.
In some cases, however, it may be prescribed for pain as part of a clinical trial.
What about 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 medical cannabis safe?
The risks of using cannabis products containing THC (the chemical that gets you high) are not currently clear. That’s why clinical trials are needed before they can be used. “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.
What are the side effects?
Depending on the type of medical cannabis you take, it’s possible to develop side effects such as:
- decreased appetite
- feeling sick
- a behavioural or mood change
- feeling very tired
- feeling high
- suicidal thoughts
If you experience any side effects from medical cannabis, report these to your medical team. You can also report them through the Yellow Card Scheme.
CBD and THC can affect how other medicines work. Always discuss possible interactions with a specialist.
CBD can also affect how your liver works, so doctors would need to monitor you regularly.
How do I get a prescription?
You cannot get cannabis-based medicine from a GP – it can only be prescribed by a specialist hospital doctor.
And it is only likely to be prescribed for a small number of patients.
A hospital specialist might consider prescribing medical cannabis:
- for epilepsy – if you (or your child) have one of the rare forms of epilepsy that might be helped by medical cannabis
- for MS – if you have spasticity from MS and other treatments for this are not helping
- for chemotherapy – if you are vomiting or feeling sick from chemotherapy and other anti-sickness treatments are not helping
The specialist will discuss with you all the other treatment options first, before considering a cannabis-based product.
A prescription for medical cannabis would only be given when it was believed to be in your best interests, and when other treatments had not worked or were not suitable.
It’s expected this would only apply to a very small number of people in England.
If the above does not apply to you, do not ask a GP for a referral for medical cannabis.
Will the laws on cannabis be relaxed?
The government has no intention of legalising the use of cannabis for recreational (non-medical) use.
Possessing cannabis is illegal, whatever you’re using it for. That includes medical use cannabis products, unless these have been prescribed for you.