A new study on cannabidiol (CBD) oil in New Zealand suggests it can help with chronic pain and mental health symptoms.
It comes after New Zealand researchers recently voiced concerns about a lack of data on the effects of cannabis, ahead of this year's referendum.
Four hundred people were included in the study, all of whom had been assessed for treatment at GP Graham Gulbransen's medicinal cannabis clinic in Auckland.
As part of the joint study with the University of Auckland, patients were asked to self-report their quality of life and side effects from before getting the treatment, through to taking the CBD oil for four weeks.
Only 250 of the patients actually rated their results and 70 per cent of them reported good, very good or excellent benefit from CBD use, according to the study.
"The findings are consistent with other evidence and underline the need for more research to allow us to fully realise the therapeutic potential of medical cannabis," lead author professor Bruce Arroll says.
Because the results were self-reported by the patients, the study's authors warn they can't know whether or not the placebo effect was factored in.
It found patients with non-cancer pain symptoms and mental health-related symptoms reported improvements including improved ability to complete activities and less pain, anxiety and depression.
“Our findings show that CBD is well-tolerated in most patients and can markedly ease symptoms in a range of hard-to-treat conditions, and that there are people keen to access this and self-fund the medication (about $300 per month),” Dr Arroll says.
Referendum ahead for legalisation of cannabis
The legality of cannabis is in the air ahead of the 2020 election, when people will be asked to vote in a referendum.
The treatment examined in this latest study is CBD - a substance found in cannabis, but doesn't contain the element that makes people high.
CBD was legalised in 2017 as a prescription medicine.
But the referendum is around general cannabis, not solely medicinal, and not solely CBD.
Erik Messamore, a psychiatrist at Northeast Ohio Medical University, says the risk of harm is real.
However, he told TVNZ1's Breakfast that doesn't necessarily mean it should remain banned.
"To me, banning cannabis makes no more sense than banning cigarettes or banning alcohol," he said this morning.
"In the US we tried to ban alcohol, we found we couldn't do it… It just doesn't work. Telling people 'no' is not effective.
"You could say because of prohibition, cannabis has become more popular in the world than ever before."
He wants people to get their information from independent scientific organisations instead of people who are likely to profit from legislation.
He pointed to studies that have found credible risk including severe anxiety, panic attacks and psychosis.
Even in today's study, with only CBD oil, 10 per cent of patients reported side effects including sedation and vivid dreams.
Two reported their pre-existing condition worsened.
Despite those risks, Dr Messamore says he's still pro-legalisation.
"People who want to use cannabis will acquire cannabis regardless. You create a black market and you create legends around cannabis," he says.
"If cannabis is secret and forbidden and in the shadows, then people who love it will tell everybody how much they love it and that's all you hear.
"If it's out in the open, we can know about its risks."