A leading UK psychiatrist has urged doctors to embrace medical cannabis in the same way as they once did another natural, relatively untested medicine — penicillin.

Professor David Nutt, a psychiatrist and neuropsychopharmacist argues in an essay in the BMJ that the medical profession should welcome medical cannabis and broaden access to it, so that its full potential can be realised.

“About 70 years ago another natural medicine came into the medical arena,” writes Professor Nutt, of the Imperial College in London.

“This was welcomed enthusiastically by UK doctors, even though there had been no placebo-controlled trials of its efficacy because it was seen to fulfil a major clinical need.