The government has accepted recommendations to ban a range of semi-synthetic cannabis compounds, including hexahydrocannabinol (HHC), following warnings from drug experts about their potential health risks.
Dame Diana Johnson, Minister for Policing and Crime Prevention, confirmed on 20th August that she would implement controls on 12 named compounds under the Misuse of Drugs Act 1971 when parliamentary time allows.
The decision follows advice from the Advisory Council on the Misuse of Drugs (ACMD), which warned that these substances – found in vapes, sweets and e-liquid cartridges – can cause serious health problems including seizures, heart complications and psychosis.
The ACMD’s report, published in May 2025, highlighted the increasing detection of HHC and other semi-synthetic cannabinoids (SSCs) across Europe and the UK since 2019. These compounds are created by manipulating the structure of naturally occurring cannabidiol (CBD) and have similar psychoactive properties to THC, the main psychoactive component of cannabis.
“Most SSCs are produced through the process of manipulating the structure of the naturally occurring compound cannabidiol (CBD) and have similar psychoactive properties to tetrahydrocannabinol (THC),” the ACMD stated in its covering letter to the minister.
The compounds to be banned include various hexahydro-derivatives such as HHC and HHCP, THC derivatives like 11-OH-THC, and THC precursors including THCA-A and THCA-B.
The ACMD’s review said it had found evidence of serious health harms from these substances, including neurological effects such as drowsiness, cardiovascular problems including rapid heart rate and chest pain, and psychiatric symptoms including anxiety, hallucinations and panic attacks.
More severe effects have occasionally been reported, including seizures, metabolic acidosis and muscle breakdown requiring hospital admission and sometimes mechanical ventilation. Children and adolescents have also been affected.
“There is accumulating evidence of the similarity in pharmacology as well as chemistry of many of these uncontrolled examples to Δ9-THC,” the ACMD concluded in its report.
Dame Diana Johnson accepted all three recommendations from the ACMD. In addition to banning the named compounds, she agreed to consult on updating the UK’s generic definition for cannabinoids to capture future psychoactive substances in this category.
“I recognise the significant health and social harms that hexahydrocannabinol (HHC) and other semi-synthetic cannabinoid (SSCs) can have and I am grateful for your advice on how best to reduce those harms and maintain public safety,” Johnson wrote in her response.
She also accepted recommendations to improve public information about these substances. The FRANK website has already been updated to include information about SSCs, and the Department of Health and Social Care will work with other departments to provide information across the UK.
Before implementing controls on two THC precursors (THCA-A and THCA-B), the government will consult with relevant stakeholders due to their “longstanding status as uncontrolled substances” to reduce the risk of unintended consequences for the cannabis industry.
The compounds will be classified as Class B substances under the Misuse of Drugs Act 1971 and placed in Schedule 1 of the Misuse of Drugs Regulations 2001, alongside other controlled drugs.
