Sir, – In the first decade of this century, “headshops” across Ireland sold unregulated recreational drugs, which led to widespread psychiatric harm. Antiquated legislation (Misuse of Drugs Act 1977) required a prolonged process of specifically nominating harmful drugs in legislation. This led to a “Hydra” phenomenon whereby the ban of one substance served only to prompt the sale of yet more; as vendors could stock shelves with a new drug that was unnamed in legislation. Lawmakers were unable to keep pace, and the proliferation of unregulated drugs led to a nationwide spike in drug-related admissions to psychiatric hospitals.
Recognising the need to proactively prevent psychiatric harm caused by these untested drugs, the government enacted legislation – the Criminal Justice (Psychoactive Substances) Act 2010 – that broadly banned the sale of any psychoactive substance. This legislation was a remarkable success, almost removing the headshops overnight and also reducing the amount of psychiatric hospitalisations in Ireland. However, the lessons learned from this era appear to have been forgotten, as shown by the rise of Hexahydrocannabinol (HHC) and other semi-synthetic cannabinoids regularly sold as vapes.
HHC and other semi-synthetic cannabinoids are manufactured to be similar in chemical structure and effect to Delta-9-Tetrahydrocannabinol (THC), the substance in cannabis that causes its high. It was widely sold in Ireland from 2022, despite psychiatrists, parents and users warnings of its psychoactive effects and the risk of triggering psychotic illness. Psychosis is a severe mental health disorder and impacts the developing brain, meaning it is especially catastrophic when it occurs in a young person. Research has shown HHC to be the second most used drug in people presenting to hospital with psychosis. The Government eventually banned its sale in July 2025 under the outdated Misuse of Drugs Act, rather than under the Psychoactive Substance Act.
This narrow banning has, predictably, resurrected the Hydra of years ago. Online and high-street vape shops have pivoted to new semi-synthetic cannabinoids, virtually identical to HHC. We are now seeing the effects of these new drugs on our psychiatric wards and in our psychosis clinics. Our patients tell us they can still easily purchase HHC in shops; but given the unregulated nature of the market, what exact semi-synthetic cannabinoid these products contain is unknown.
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We therefore urge the Government to review why the Criminal Justice (Psychoactive Substances) Act 2010 was not used to prohibit the sale of HHC in a more timely manner. We also call on the Government to issue a clear policy directive affirming that the 2010 Act is the primary and most appropriate legislative tool for controlling new psychoactive substances, to avoid a repeat of nearly two decades ago. – Yours, etc,
Dr Brian O’Mahony, senior registrar in psychiatry, Carrigtwohill, Co Cork,
Prof David Cotter, consultant psychiatrist at Beaumont Hospital,
Prof Colm McDonald, consultant psychiatrist at University Hospital Galway,
Prof Bobby Smyth, clinical professor at Trinity College Dublin,
Dr Brian Hallahan , consultant psychiatrist at University Hospital Galway,
Prof Brian O’Donoghue, consultant psychiatrist at St Vincent’s University Hospital.
