Semi-synthetic cannabinoids
HHC · hexahydrocannabinol · HHCP · HHC-P · hexahydrocannabiphorol · HHC acetate · HHCO · HHC-O · HHCH · THCP · semi synthetic cannabinoids
What does current UK evidence show?
The ACMD’s May 2025 review confirmed UK analytical detections of HHC, HHCO-acetate and HHCP, with HHC detected most often. The evidence does not measure national use, market share or a reliable UK trend. European poisoning and market reports justify surveillance but cannot establish the scale of UK harm. EUDA’s 2026 report describes changing products and undeclared cannabinoids; a retail label cannot verify a batch’s composition.
Overview
Identity, legal classification, form and pharmacological context
- Drug category
- Cannabinoids · Synthetic drugs
- Common names
- HHC, hexahydrocannabinol, HHCP, HHC-P, hexahydrocannabiphorol, HHC acetate, HHCO, HHC-O, HHCH, THCP, semi synthetic cannabinoids
- Typical forms
- Vape liquids and cartridges, oils, sweets and other edibles, and plant material coated with cannabinoids. Product names, percentages and packaging may not match laboratory findings. These products are not equivalent to a regulated prescribed cannabis preparation.
- Routes
- Vaped, smoked or swallowed, depending on the product. Edibles are absorbed more slowly than inhaled products, so early effects may not indicate the eventual intensity. Nicotine-vape use and exposure to an undeclared intoxicating cannabinoid require separate recording.
- UK legal classification
- Compound-specificAt 12 October 2026, HHC and HHCP are not captured by the existing MDA cannabinoid definition identified by the ACMD; psychoactive non-exempt products are subject to the Psychoactive Substances Act 2016. HHC acetate also falls outside that existing definition. Delta-8-THC, delta-9-THC, THCP and relevant THC esters are already Class B. A draft Order laid on 14 September 2026 proposes Class B controls for HHC, HHCP and further derivatives, but it is not yet in force: proposed commencement is 28 days after being made. International scheduling does not itself enact UK classification. Absence of an MDA class does not make unrestricted sale lawful.Check government source ↗
- Concise pharmacology
- HHC activates cannabinoid receptors and can produce THC-like intoxication. Semi-synthetic usually describes chemical modification of a plant cannabinoid such as CBD, but HHCP and some other products may be manufactured wholly synthetically. They remain structurally different from many Spice-type SCRAs. Receptor activity, mixtures of isomers and human potency vary; advertising claims of precise potency multiples are not a reliable clinical guide.
Main harms
Concise clinical and polydrug picture
Reported poisonings include dizziness, drowsiness, confusion, anxiety, palpitations, nausea and vomiting. Severe psychiatric or neurological effects and reduced consciousness have also been reported. French poison-centre observations support a toxicity signal, but selected reports cannot tell us how frequently such outcomes occur in UK users.
Long-term health outcomes and risks from manufacturing impurities remain poorly characterised. Cannabis-related knowledge provides reasons for concern but cannot establish an identical long-term risk profile for HHC, HHCP or every derivative. Product-specific evidence is required.
Dependence is plausible from cannabinoid pharmacology; some users report sleep disturbance and low mood after stopping. Human studies do not yet define reliable incidence or a standard withdrawal syndrome for each compound. Persistent or severe symptoms warrant clinical assessment.
Alcohol, sedating medicines and other cannabinoids may add to impairment. Direct interaction studies are scarce, especially for HHCP. Unknown ingredients prevent reliable prediction from a brand name. Co-use and prescribed medicines should be recorded when assessing a poisoning.
Delayed edible effects can lead to unintended repeated consumption, and sweet-like products create accidental child-exposure risks. Vaping exposes the lungs to a chemically variable formulation. A product described as CBD or legal is not assurance that it is non-intoxicating or free of other drugs.
Current intelligence status
Assessment, confidence and direction
The ACMD’s May 2025 review confirmed UK analytical detections of HHC, HHCO-acetate and HHCP, with HHC detected most often. The evidence does not measure national use, market share or a reliable UK trend. European poisoning and market reports justify surveillance but cannot establish the scale of UK harm. EUDA’s 2026 report describes changing products and undeclared cannabinoids; a retail label cannot verify a batch’s composition.
Reason: Limited confidence in the extent and direction of UK exposure. Compound identity has been analytically established in selected samples, but routine toxicology may miss newer cannabinoids. Clinical reports often rely on self-reported products, and human safety data for HHCP are especially sparse. The classification refers to surveillance coverage, not reassurance about an individual product.
Principal source limits: UK analytical coverage is incomplete. HHC was detected more often than HHCP; neither detection counts nor overseas poisonings estimate national use. Early review with substantial human-data gaps; not a source for current UK legal status or market size.
Geography and reference periods are given in each linked source card below. The rating is an editorial evidence judgement, not a probability, clinical risk score or TD priority.Available UK evidence is too limited or unrepresentative for a stronger trend judgement.
Operational implications
Evidence-supported prompts for professional response
Commissioners should support targeted surveillance and analytical capacity. Treatment and emergency teams should distinguish reported product identity from confirmed exposure and seek toxicology advice for severe presentations. Public-health messages should explain the differences between cannabis, these THC-like products and Spice. Review the legal note when the draft Order is made and its commencement date is confirmed.
Record substance, sold identity, route, frequency and combinations; review physical, mental-health and dependence needs.
Use symptom-led assessment and escalate reduced consciousness, seizures, overheating, chest pain or severe agitation.
Send unexpected products or incidents through agreed testing and alert routes; distinguish confirmed results from preliminary reports.
Related intelligence
Continue into connected platform evidence
Sources & limitations
Direct evidence links, reference periods and status
Semi-synthetic cannabinoids related to tetrahydro-cannabinol and cannabidiol
Published22 May 2025Reference periodUK and international evidence reviewed in 2024–2025
UK analytical coverage is incomplete. HHC was detected more often than HHCP; neither detection counts nor overseas poisonings estimate national use.Hexahydrocannabinol (HHC) and related substances
Published17 Apr 2023Reference periodTechnical pharmacology and product review
Early review with substantial human-data gaps; not a source for current UK legal status or market size.Hexahydrocannabinol poisoning reported to French poison centres
Published2024; online 1 Mar 2024Reference periodSelf-reported exposures 1 Jan 2022–31 May 2023
Selected French poison-centre cases; limited analytical confirmation and no population denominator.New psychoactive substances: the current situation in Europe
PublishedJune 2026Reference periodEuropean Drug Report 2026; most supply data refer to 2024–2025
European market signals and survey findings must not be relabelled as UK prevalence, UK growth or UK law.Draft Misuse of Drugs Act 1971 (Amendment) Order 2026
PublishedLaid 14 Sep 2026Reference periodDraft legislation checked 12 Oct 2026
The draft has no made date; its proposed commencement is 28 days after being made. It must not be described as an enacted Class B control.Misuse of Drugs Act 1971 (Amendment) Order 2026: parliamentary record
Published14 Sep 2026Reference periodStatus checked 12 Oct 2026
Draft affirmative procedure. Parliamentary consideration and approval do not alone establish commencement.Psychoactive Substances Act 2016: guidance for researchers
Published20 May 2016Reference periodAct commenced 26 May 2016
PSA offences and exemptions depend on the activity and circumstances; absence of MDA classification is not unrestricted legal supply.