Cannabis, which has probably been around since the last millennium, looks set for a renaissance in the new one. Not one but two trials are planned to test its medicinal benefits. In addition to the MRC study of patients with multiple sclerosis, GW Pharmaceuticals - the only company with a Home Office licence to grow the drug - is planning a trial on 2,000 patients with MS, spinal cord injury and intractable pain.
This is excellent news, though it has been slow in coming. It is two years since the British Medical Association suggested controls on prescribing cannabis derivatives be relaxed to allow research to go ahead, after indications that it could be effective against conditions ranging from nausea to epilepsy. There is little doubt it has been held up by the public fear of recreational drugs. That fear, as applied to cannabis, is misplaced.
When my teenage sons began experimenting with cannabis, I was more relieved than alarmed. I reckoned it ought to mean less drinking and, on the principle of harm reduction, should bring a net benefit. I laid down conditions - they had to be discreet (no clouds of blue smoke billowing down the stairwell), and there was a ban on smoking during the day - but I was otherwise tolerant. Keeping the lines of communication open has always seemed more important - and feasible - than controlling which substances passed their lips.
Some support for this view came from The Lancet. In an editorial published a year ago, the medical journal concluded that cannabis was less harmful than alcohol or tobacco and that "the desire to take mood-altering substances is an enduring feature of human societies worldwide and even the most draconian legislation has failed to extinguish this desire".
It suggested that patients thinking of trying cannabis for relief were entitled to know the risks - accidents when intoxicated, irritation of the lungs, dependence with daily use and subtle cognitive impairment with long-term use. Compared to the damage wreaked by smoking and drinking, however, these dangers were not excessive, it said.
Strangely no one has yet suggested a trial of one of cannabis's best known, but least discussed, effects - its enhancement of sex. In all the words written about Viagra, I don't recall a mention of its natural alternative. When the Impotence Association funds a trial, cannabis's renaissance will be complete.