Study leader Louisa Degenhardt found nearly 13 per cent of 1500 chronic pain patients, who were mainly aged in their late 40s and early 50s, had used cannabis in the past year despite being prescribed opioids. This compared to only 4.7 per cent of the rest of the population, she wrote in the journal Drug and Alcohol Dependence. "One in three said they found it very effective to relieve their pain, that's a score of ten out of ten," she said. "Now these are all subjective scores … but it means there is definitely a group of people who think that taking it was very beneficial." Professor Degenhardt, from the National Drug and Alcohol Research Centre and the University of Melbourne, said the study raised important questions about whether the benefits of cannabis for pain should be more seriously explored, but also about the negative effects of drugs, such as patient dependence. "The people who were also trying cannabis for pain, they were younger but they had also been living with pain for longer," she said. "Their pain was so severe it had been interfering with their lives."

Study co-author Nicholas Lintzeris, a medical doctor specialising in addiction and an associate professor of addiction medicine at the University of Sydney, said there had been a huge rise in the number of Australians seeking treatment for addiction to pain medications. This was linked to a lack of multi-disciplinary treatment such as physiotherapy and massage, leaving doctors with little choice but to prescribe heavy-duty painkillers, or even other drugs for which there was little evidence of efficacy, such as antidepressants or antipsychotics. "Interestingly, in the United States (as there has been more use of medicinal cannabis there), we are starting to see some large epidemiological studies that indicate cannabis use might ... provide other options other than simply an ever-escalating opioid dose [when treatment isn't working]," he said. "It could well be that if there were safer cannabinoid drugs that might be a useful strategy". However, he said there was little known about the cannabis plant, which contains many different chemicals. The Baird state government has committed to beginning three trials of medical cannabis, for children with the most severe form of drug resistant epilepsy, and people with terminal illnesses and chemotherapy-induced nausea. The Labor party has called for the process to be expedited given the existing evidence for it, while

Greens NSW MP John Kaye said the NDARC paper provided more evidence that both the Liberal and Labor parties were being too cautious. "It is irrational and cruel to criminalise patients who are obtaining relief from chronic non-cancer pain using medicinal cannabis," he said. "Waiting for yet more evidence before changing the law is a delaying tactic that will see tens of thousands of people suffer debilitating levels of pain needlessly."