Doctors said the recreational drug, smoked illegally by millions, had a valuable role in relieving suffering in certain patients who were being denied it by an outmoded law.
Research had shown that some of the 60 psycho-active substances among the 400 chemicals contained in cannabis can reduce nausea in cancer patients having chemotherapy, and can help people with cerebral palsy, multiple sclerosis and associated conditions control their movements. Only two cannabis derivatives are licensed and their use is restricted to the treatment in hospital of cancer patients with nausea.
The annual conference of the BMA, meeting in Edinburgh, called for a wider range of cannabinoids to be licensed and their use permitted by patients outside hospital. The drugs would be taken orally as an aerosol or by injection, but would not be smoked and their use would be limited to sufferers from a defined list of medical conditions.
Steven Hajioff, senior lecturer in general practice at St Bartholomew's hospital, London, said: "The sick and dying should be able to turn to the doctor for help - not to the drug dealer. This is humane, based on sound science, and it would help keep patients out of the hands of criminal and evil elements."
Hundreds of patients were flouting the law to obtain the drug they needed and some were going to prison as a result, the conference was told. However, Edward Tierney, a GP in Rochdale, warned that cannabis had unpleasant effects, including distorting perception, reducing vigilance and causing apathy and indifference. The drug remained in the body for 28 days and, when smoked, delivered three times as much tar and five times as much carbon monoxide as cigarettes.
"Cannabis is a dirty drug. Alternatives must be found. For an association that wants to banish tobacco there cannot be any justification for legalising cannabis," Dr Tierney said.
The Multiple Sclerosis Society said the BMA's decision was premature. In a reversal of the normal roles, the patients group called for more research.
Peter Cardy, the chief executive said: "We are very surprised that doctors should be advocating wider use of substances derived from cannabis before convincing scientific trials have taken place."
A report examining the scientific evidence drawn up by the association's Board of Science, which is understood to recommend wider use of the drug, is to be considered by the BMA's council in September. An appeal by the association's leaders to defer a decision until then was rejected by the conference.
Upen Pati, a GP from Sefton, Lancashire, said: "We've been waiting for this for ten years. Thousands of suffers are anxious to have a decision now."
Earlier, the conference condemned manufacturers of alcopops for targeting teenagers with strong drink that could have lethal effects. Robin Davies, a consultant paediatrician from Gwynedd, said the average district hospital admitted one or two under-15-year-olds every weekend who were comatose with alcohol, and they were only the tip of the iceberg.Reuse content