The political push for cannabis to be legalised for pain relief because “people are suffering now” is morally and socially irresponsible because it  ignores medical findings that the drug is a poor pain reliever and can be harmful, a specialist pain medicine physician has warned.

“There is little evidence to support the use of marijuana for pain apart from personal testimonials,” says Dr Dilip Kapur, a specialist pain medicine physician in Adelaide.  “That is not science. Facebook outreach and Twitter outreach is not science.

“The medical evidence from trials that have been done suggests that marijuana does not work well at treating the kinds of pain we regularly encounter – from nerve damage to amputations, musculoskeletal pain and cancer pain. It comes off second best to existing drugs by a very long chalk.

“Marijuana would also fall at the first hurdle in terms of its safety profile. One of the most alarming results came from a UK trial about 10 years ago that looked at a marijuana-based extract for acute pain after surgery. They had to stop the trial because of a series of safety concerns: serious psychiatric and heart problems arose in some patients.

“But no one’s too interested in that trial now.”

Dr Kapur will speak on ‘Medical marijuana’ in Adelaide on Friday September 16 at a conference of the Faculty of Pain Medicine (FPM) of the Australian and New Zealand College of Anaesthetists. His concerns are supported by FPM’s policy on cannabis, which does not support the use of cannabinoids in chronic, non-cancer pain “until such time as a clear therapeutic role for them is identified in the scientific literature”.

He warns that the social pressure to legalise medicinal marijuana is a Trojan horse that owes too much to “an activist lobby that wishes to have the same access to cannabis as is currently permitted for alcohol and tobacco. They want access to marijuana without being hassled by police. This is a societal issue; there will be unavoidable medical and social consequences of increased cannabis use.  The decision to be made is whether society in general is willing to accept those consequences?”

Dr Kapur says that the US State of Colorado legalised cannabis for medical use in 2000 based on estimates that among its population of 5 million people – about the size of Victoria – there would only be 4000 people who qualified to use it. “Within a few years that had increased to 12,000, and then the floodgates opened and about 115,000 people ended up on so-called ‘medical’marijuana, most of it for purely recreational use. It couldn’t keep going like that, so in 2012 Colorado was forced to legalise it for use by anyone aged over 21. The marijuana industry there is now estimated at a billion dollars a year.

“The societal costs are unknown, but some markers are worrying.  For example, the rate of fatal road accidents in Colorado associated with cannabis intoxication, particularly involving visitors from other states, increased sharply after medical marijuana legislation.”

Dr Kapur cast doubt on other medical uses for cannabis too, saying there was no evidence  it had  any clear advantage over other drugs in the treatment of muscle spasm in multiple sclerosis. When it comes to relieving nausea from chemotherapy, today’s more sophisticated drugs do a better job with fewer side effects, he says.