MPS will debate a call for the legal status of the hallucinogenic substance found in ‘magic mushrooms’ to enable research for treatments for conditions such as depression and PTSD.

Some states in the USA have legalised the use of psilocybin, which is found in more than 50 species of fungi, while Australia will allow the prescription of medicines containing it and MDMA from July this year.

But in the UK there are concerns research is being “significantly stalled” as the substance is listed under the most stringent class of drugs and is currently more controlled than heroin.

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The SNP’s Ronnie Cowan is one of three MPs who will be opening a debate in the House of Commons on Thursday, with a motion which calls on the UK Government to take steps to conduct an urgent review of the evidence for psilocybin’s current status in drugs law.

He told The National: “The issue with psilocybin is that it is being used in other countries after medical research to treat PTSD, schizophrenia and other psychological disorders as well.

“We have got real difficulty doing that here in the UK because the categorisation of psilocybin is one of the most dangerous drugs we have got.

“For medical researchers to get the drug, store it safely and then use it in a responsible fashion, it is very, very difficult because of the classification of the drug.

“If you loosen that up it makes it easier for the research to be done, and the more research that can be done, the more we learn about the pros and cons of it and how to use it responsibly.”

The National:

Cowan said psilocybin was not a “magic bullet” and the debate would not cover the topic of microdosing – where people take small doses of psychedelic drugs to boost mental health.

“That tends to be more of a recreational scene and is not what we are talking about,” he said.

“It is about shining some light onto the recognised medical benefits and the proper medical use of psilocybin.

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“We’ve always given psilocybin and LSD a really bad reputation as they have always been associated with hippy type culture, whereas it is the medical profession who want to develop this product.

“But because we categorise them wrongly back in 1971 and we continue to do so ever since, it has simply been too difficult for any responsible medical research to be done on the product.

“We are trying to change that so that correct medical research can be done – and then decisions can be made based on knowledge.”

The motion states that “psilocybin, a naturally occurring compound, has the potential to revolutionise the treatment of many of the world’s most hard to treat psychiatric conditions such as depression, PTSD, OCD, addiction and anorexia nervosa”.

But it goes on to state that "no review of the evidence for psilocybin's current status under UK law has ever been conducted” and that “psilocybin is currently more controlled than heroin under the most stringent class and schedule under UK law which is significantly stalling research”.