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Psychedelics and related substances (PARS) could potentially help treat a wide range of mental illnesses, but more evidence is needed to support their routine use in clinical settings, the Royal College of Psychiatrists (RCP) has said.
On 19 September 2025, the RCP said that there is growing interest in the use of PARS in the treatment of mental illnesses, either alone or combined with psychotherapy. However, it added that while results of early clinical studies of non-ketamine drugs have been encouraging, “high-quality evidence on the efficacy of these substances remains limited”.
Evidence is needed on the mechanism of action of the substances and on adverse effects associated with prolonged use of the drugs, the RCP added.
However, it noted that many of these substances are listed under Schedule 1 (Class A), which is one of the “socio-political barriers” to conducting this type of research — with the exception of ketamine — which is licensed for anaesthesia and esketamine for major depressive disorder.
As well as more research, the RCP is calling for the creation of a centralised patient database to monitor the use of PARS, as well as gather information on the effects of these substances.
Owen Bowden-Jones, registrar of the RCP, said: “New treatments are rarely developed for people with mental illness, whose needs are often overlooked, and it’s vital that this trend is reversed. That is why we are calling for further research into psychedelics as potential treatments for people with certain conditions, such as depression and PTSD [post-traumatic stress disorder], including those who are less responsive to other forms of care.
“Further high-quality research into these substances is still needed, and it’s important that the hype surrounding their use isn’t prioritised above good clinical practice.”
David Nutt, Edmond J Safra chair and director of the Neuropsychopharmacology unit in the division of brain sciences at Imperial College London, said it was “good that this report recognises that research on psychedelics has been severely limited by legal restrictions around the use of these substances in research”.
“I had hoped, therefore, that the report would go further to recommend a change to the Schedule 1 status of the most promising of these substances which would be the most effective way to remove these research barriers and collate more evidence in this space. Such a change was made in Australia nearly two years ago with considerable benefit to patients and no untoward effects.”
Amira Guirguis, chair of the Royal Pharmaceutical Society’s science and research committee, said: “Psychedelics may hold promise in treating conditions such as depression, anxiety and PTSD, particularly where existing options have failed. But there are still significant gaps in our understanding of their long-term safety and effectiveness, as well as important regulatory, ethical and clinical considerations.
“Further robust clinical trials are essential to assess their role in healthcare, ensuring patients are supported and risks such as adverse psychological experiences are carefully managed. The evidence must guide practice before these treatments can be considered in routine care.”
Steve Bazire, honorary professor at the University of East Anglia School of Pharmacy, said: “The area of psychedelics for depression, PTSD and other intractable conditions is, as the RCP say, rapidly expanding. The call for more data is appropriate — we can always use more data – but, as is mentioned, all these drugs are Class A substances. This makes research in the UK incredibly difficult, lengthy and costly to carry out, such that many people are unable to even start research. The storage facility requirements alone can be prohibitive. Subsequently, sufficient research will likely only occur in the UK if there is some relaxation of these blanket and blanket rules.
“[A centralised database] sounds an interesting idea. It would need to cover a range of diverse compounds but could produce some good naturalistic data in the same way that the Twenty/21 cannabis study has achieved.”
A systematic review published in the BMJ in August 2024 reported that psilocybin — the active ingredient in ‘magic mushrooms’ — could be as effective as escitalopram, a selective serotonin reuptake inhibitor, in treating depressive symptoms.
In August 2025, the National Institute for Health and Care Research (NIHR) announced the largest ever trial of ketamine to treat severe alcohol use disorder, which would launch across eight NHS sites in England.
NIHR is also funding a trial looking at whether psilocybin can help prevent relapse in people recovering from opioid addiction.
