Having previously admitted the profession “got it wrong” with opioids, Dr Chris Hayes is worried that we have not learned from past mistakes and fears we “may be exposing the community to risk” by forging ahead too quickly.

Dr Hayes is the director of the Hunter Integrated Pain Service at John Hunter Hospital, as well as Dean of the faculty of pain medicine for the Australian and New Zealand College of Anaesthetists.

In an article in the College of Anaesthetists’ Bulletin this week, Dr Hayes says the political agenda and community advocacy for medicinal cannabis are out of balance with the medical evidence.

“I have some concerns as to who might be promoting the agenda of broadening access to cannabis and what might be their motivations, be it financial or otherwise, because the push hasn’t really come from the healthcare sector, which is interesting,” he told the Newcastle Herald.

“There has been very little push and much more of a caution voice coming from the health and research sectors.”

In his field of chronic pain, a “reasonable amount of research” had been discouraging of the role of cannabis.

“Various expert groups have recommended that it’s not a productive area to look at, but when you look at the community advocacy and the legislative process that is going ahead, that always seems to want to include chronic pain, which is a big market because 20 per cent of the population have chronic pain,” Dr Hayes said.

While there was no “solid evidence” cannabis should be used at all medically, Dr Hayes said there were some studies underway in NSW that looked at whether there were benefits for chemotherapy-induced vomiting and nausea, end-of-life symptom management, and for unmanageable paediatric epilepsy.

“There is some work starting that will be very helpful in clarifying this,” he said.

Dr Hayes said his colleagues in the medical community had been surprised by the haste with which medicinal cannabis had been pushed through parliament for legislation.

A degree of caution was usually the norm, especially in regards to a drug known to have toxicity.

In the past, there had been an over-reliance on prescription opioids to treat chronic pain, contributing to climbing rates of demand and addiction.

Dr Hayes said we were still “reaping the difficulties” of a gross over-prescribing of that medication.

“Until the evidence of medicinal cannabis is available, caution is warranted,” he said.

The areas where medicinal cannabis might prove effective in time, such as paediatric epilepsy, were niche areas with only a small number of people likely to benefit.

“That’s only a small number of children around Australia, so you don’t need a multi-billion dollar cannabis industry to support their use,” Dr Hayes said. “I just smell a little bit of vested financial interest in this.”

Dr Hayes said reports from the US showed enormous growth in the multi-billion dollar cannabis industry in coming years.

“There needs to be a more transparent conversation over what the product is that is being sold, and who might be the beneficiaries of that,” he said.

“There is some rhetoric around stopping little children from having seizures, which may be part of it, but I suspect it is not the main part based on the lack of research to support that yet.”

Dr Hayes said legislation had already changed in NSW, with other jurisdictions poised to follow. The new regulations had enabled doctors to apply for approval from NSW Health to prescribe unregistered cannabis-based medicines where potential benefits and harms were balanced.

For years the Holy Grail in opioid research had been isolating a pain treatment that would deliver relief without side effects, he said.

Cannabinoid research had a similar challenge, as the psychoactive THC component seemed vital for meaningful analgesic activity.

“This correlates with the clinical observation that unless a patient is ‘stoned’ there is little analgesic impact,” Dr Hayes said.