HHC (Hexahydrocannabinol)

The drug HHC (Hexahydrocannabinol) is now a Schedule 1 controlled drug under the Misuse of Drugs Act 1977. This means that the import, export, production, possession, sale, and supply of products containing HHC is now illegal.

HHC is one of 14 new substances, including several semi-synthetic cannabinoids and a novel benzodiazepine that have been newly classified as controlled drugs. This was done by a Declaration Order made by the Government of Ireland on 29 July 2025. It gives added powers of enforcement to An Garda Síochána combatting the trade in illicit drugs. A full list of the substances is available below.

The Misuse of Drugs Act 1977 regulates and controls the import, export, production, supply and possession of controlled drugs. Schedule 1 controlled drugs are those which have no medical or therapeutic value and no commercial use and which present a very high risk of abuse.

The 14 new substances to be declared as controlled drugs were identified by the EU and by the UN Commission for Narcotic Drugs as posing a serious risk to public health.

Additions to the Schedules of the Misuse of Drugs Regulations 2017:

Schedule 1

• N-[1-(Aminocarbonyl)-2,2-dimethylpropyl]-1-butyl-1H-indazole-3-carboxamide (otherwise known as ADB-BUTINACA
• N,N-diethyl-2-[(4-butoxyphenyl)methyl]-5-nitro-1H-benzimidazole-1-ethanamine (otherwise known as Butonitazene
• N,N-diethyl-5-nitro-2-[(4-propoxyphenyl)methyl]-1-H-benzimidazole-1-ethanamine (otherwise known as Protonitazene)
• 2-[(4-Ethoxyphenyl)methyl]-N,N-diethyl-1H-benzimidazole-1-ethanamine (otherwise known as Etazene)
• 2-[(4-Ethoxyphenyl)methyl]-5-nitro-1-(2-piperidin-1-ylethyl)-1H-benzoimidazole (otherwise known as Etonitazepipne)
• 2-[(4-Ethoxyphenyl)methyl]-5-nitro-1-(2-pyrrolidin-1-ylethyl)-1H-benzoimidazole (otherwise known as Etonitazepyne)
• N-ethyl-2-[2-[(4-isopropoxyphenyl)methyl]-5-nitro-benzimidazol-1-yl]ethanamine (otherwise known as N-desethyl isotonitazene)
• 2-(2-fluorophenyl)-2-(methylamino)cyclohexan-1-one (otherwise known as 2-Fluorodeschloroketamine
• 6a,7,8,9,10,10a-hexahydro-6,6,9-trimethyl-3-pentyl-6H-dibenzo[b,d]pyran-1-ol (otherwise known as Hexahydrocannabinol)
• Hexahydro derivatives of 3-alkyl homologues of cannabinol
• 2-[(4-methoxyphenyl)methyl]-5-nitro-1-(2-pyrrolidin-1-ylethyl)-1H-benzoimidazole (otherwise known as Metonitazepyne
• 1-{2-methyl-4-[(2E)-3-phenylprop-2-en-1-yl]piperazin-1-yl}butan-1-one (otherwise known as 2-methyl-AP-237)
• 5-nitro-2-[(4-propoxyphenyl)methyl]-1-(2-pyrrolidin-1-ylethyl)benzimidazole (otherwise known as Protonitazepyne

Schedule 4 Part 1

• Bromazolam
• Carisoprodol

HHC is categorised as a semi-synthetic cannabinoid. They are derived from the cannabis plant but altered so that they end up being chemicals that do not occur naturally. Semi-synthetic cannabinoids are mostly produced from cannabidiol (CBD) extracted from low-THC cannabis (hemp) which is similar in chemical structure of THC. Although the effects of semi-synthetic cannabinoids on humans remain poorly studied, reports suggest they are similar to those of cannabis, with risks of adverse reactions ranging from mild to severe poisoning, sometimes requiring treatment in hospital.

Some countries report increasing numbers of poisoning cases involving these substances, but systematic reporting is not currently available. The pharmacological similarity of semi-synthetic cannabinoids to THC raises concerns about their potential to trigger psychotic episodes as well as their abuse and dependence potential with Irish mental health and addiction services expressing concern for increases in occurrences as a result of HHC use.

By the end of 2024, 24 semi-synthetic cannabinoids had been identified on drug markets in Europe by the EU Drugs Agency. These substances have spread rapidly and action has been taken to control them, with HHC (hexahydrocannabinol), the first identified, reported in 27 European countries and listed as a controlled drug in at least 22 EU Member States. It was recommended for international control by the World Health Organization’s Expert Committee on Drug Dependence in November 2024.

According to laboratory studies on several animal species, HHC appears to have broadly similar effects to cannabis and THC products. The pharmacological and behavioural effects of HHC in humans have not been widely studied, though recent reports show that its effects are like that of cannabis. The effects vary from person to person. Some people will feel elevated mood, happy or euphoric. Some might feel relaxed and have an altered perception.

Anecdotal reports to the Health Service Executive (HSE) also confirm some people have experienced the following effects following the use of HHC:

• A stronger and ‘different’ type of intoxication compared with cannabis
• General feelings of being unwell
• Confusion
• Depression
• Withdrawal symptoms following frequent use
• Collapse
• Paranoia and delusions

More information on the possible effects of HHC on mental health is available from the CPI information leaflet.

The National Drug Treatment Recording System (NDTRS) is the national surveillance system that records and reports on cases of drug treatment in Ireland. It is compiled annually to provide information on treatment demand and important data to allow services to deliver what is required.

The NDTRS is funded by the Department of Health and maintained by the Health Research Board. Hexahydrocannabinol (HHC) was added to NDTRS in 2024, in addition to vaping as a route of administration. Between 1 January 2024 and 25 July 2025, 221 treatment cases were reported to the NDTRS where HHC was recorded as main or additional problem drug. Of these, 118 of these cases were treated in 2025 (up to 25 July 2025). These figures are provisional and subject to change. The majority of those treated for HHC were male and most were aged 19 or younger.

While the evidence is still emerging on the short and long term effects of HHC, two Irish studies have documented concern for the impact it can have on mental health, imcluding a recent study by researchers in University Hospital Galway which found that HHC was the second most common drug used by patients presenting with psychosis over a 21-month period.

Psychosis is a condition where people lose touch with reality with symptoms often involving delusions or hallucinations. Psychosis can be a short or long-term condition. Irish cases of HHC use include reports of extreme distress, delusions, auditory hallucinations, paranoia, detachment from reality and self-harm. More information can be found here.

Ireland’s national drugs strategy sets out a health-led approach to drug use. It recognises that drug use is first and foremost a health issue. It aims to promote healthier lifestyles within society and to encourage people to make healthier choices around drug and alcohol use. This is being achieved through education, prevention and harm reduction initiatives, and by promoting rehabilitation and recovery. It also aims to reduce access to drugs for harmful use. Controlling HHC is an important step in this regard.

Work to develop a successor National Drugs Strategy is currently underway.

It is always safer not to use drugs at all. Each person will react differently to the substances they consume, based on physical and mental health, underlying health conditions, the contents and potency of the drug they are using, the setting they are in.

The HSE operates a confidential freephone Drug and Alcohol Helpline: 1800 459 459 from Monday to Friday between 9:30 am and 5:30 pm or through email at helpline@hse.ie. information on services in your locality can be found on the Health Research Board’s interactive map.

The HSE’s website drugs.ie provides comprehensive information and support for people who use drugs and for concerned parents, families, teachers and the general public. HSE also provides information through Drugs.ie social media channels.