Medicinal cannabis can help relieve pain caused by cancer and reduce the number of drugs patients need, Canadian research suggests.
In a study of 358 cancer patients, researchers concluded it was a safe option for managing pain, alongside other drugs.
Only specialist hospital doctors can prescribe cannabis-based medicines on the NHS, mostly for severe epilepsy.
Research on how well they treat pain is still being collected in the UK.
The study, published in BMJ Supportive & Palliative Care, researchers found medicinal cannabis to be “a safe and effective complementary treatment for pain relief in patients with cancer”.
Products with an equal balance of the active ingredients tetrahydrocannabinol (THC) and cannabidiol (CBD) seemed to be the most effective.
Cannabis plants contain both – but while THC produces a “high”, CBD does not.
Of the patients studied:
- about a quarter took THC-dominant products
- 38% THC-CBD-balanced drugs
- 17% CBD-dominant products
The most common side-effects were:
The researchers, from McGill University, in Montreal, Harvard Medical School, in Boston and the Royal College of Surgeons in Dublin, among others, say about a third of all cancer patients and two-thirds of those who are terminally ill experience moderate to severe pain.
Painkillers are the standard treatment – but a third of cancer patients are still thought to experience pain.
Every three months for a year, the patients were asked:
- how much pain they felt
- how many drugs they took
After taking the cannabis medicines, they felt much less pain and noticed it interfering less with their daily life.
But more rigorous trials using a control group to compare the effects of cannabis medicines with a dummy drug are needed to confirm the findings, the researchers say.
It is very rare but since 2018 UK law has allowed the prescription of unlicensed cannabis-based medicines in very specific circumstances:
- for children and adults with rare, severe forms of epilepsy
- for adults with vomiting or nausea caused by chemotherapy
- for people with muscle stiffness and spasms caused by multiple sclerosis (MS)
Official guidance says:
- medicinal cannabis is not recommended for treating pain, or for most types of epilepsy.
- more research is needed, “particularly to understand any benefits and risks of these medicines for children and young people”
A Department of Health and Social Care official said: “Licensed cannabis-based medicines are funded routinely by the NHS where there is clear evidence of their quality, safety and effectiveness.
“Like any other medicine, unlicensed cannabis-based products for medicinal use must be proved safe and effective before they can be considered for routine NHS funding.