Psychedelic drugs including LSD and magic mushrooms are much less harmful than has been claimed, and should be reclassified to make it easier for scientists to research their potential benefits, a leading psychiatrist has said.

Promising medical research into psychedelics ground to a halt as long ago as 1967, when they were made illegal amid widespread concern about their psychological and social harms.

However, writing in the BMJ, psychiatrist Dr James Rucker, said that no evidence had ever shown the drugs to be habit-forming. There is also little evidence of harm when used in controlled settings, and a wealth of studies indicating that they have uses in the treatment of common psychiatric disorders, he said.

Researchers are beginning to look again at how LSD and psilocybin – the active compound in magic mushrooms – might be of benefit in the treatment of addiction, for obsessive compulsive disorder and even, according to one small Swiss study, to alleviate the symptoms of anxiety in terminally ill patients.

However, larger trials are “almost impossible”, Dr Rucker argues, because of the “practical, financial, and bureaucratic obstacles” imposed by the drugs’ legal status.