HHC (hexahydrocannabinol) is a semi-synthetic cannabinoid made by hydrogenating THC-type compounds in a laboratory. It occurs only in trace amounts in the plant. Like THC it is intoxicating, it can trigger a positive cannabis drug screen, and since December 2025 it has been under international control in Schedule II of the UN 1971 Convention.
HHC products spread through European shops from 2022. Formula Swiss has never sold HHC, and that is a deliberate choice: HHC is made by chemical conversion, it is intoxicating, and it is now under international drug control. This article explains what it is.
HHC, or hexahydrocannabinol, is a hydrogenated form of tetrahydrocannabinol (THC). It occurs naturally in very small amounts in Cannabis sativa, although it is more commonly produced through synthesis. It is often described as a psychoactive compound that shares certain similarities with THC.
The European Union Drugs Agency (EUDA) has noted that HHC began to attract attention in the early 2020s, especially through online platforms and speciality shops where it has been presented as an alternative to other cannabinoids.
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Key takeaways
- HHC, or hexahydrocannabinol, is derived from THC through hydrogenation.
- It is reported to produce psychoactive effects similar to those of THC.
- HHC is rarely found in cannabis plants in its natural form and is usually synthesised.
- Ongoing research is needed to better understand its properties and associated risks.
Chemical and physical data of HHC
HHC, or hexahydrocannabinol, possesses distinct chemical and physical properties. A closer look at its formula and structure provides key details relevant to laboratory and regulatory assessment.
The chemical formula of HHC is C21H32O2. Its structural formula, (6aR,10aR)-6,6,9-trimethyl-3-pentyl-6a,7,8,9,10,10a-hexahydrobenzo[c]chromen-1-ol, shows how hydrogenation alters the standard THC molecule.
Hydrogenation adds two hydrogen atoms across the one double bond in THC’s cyclohexene ring; the aromatic ring is unchanged. This creates two forms, 9(R)-HHC and 9(S)-HHC, which differ in potency.
| Chemical formula | Structure | Molar mass (g·mol−1) |
|---|---|---|
| C21H32O2 | (6aR,10aR)-6,6,9-trimethyl-3-pentyl-6a,7,8,9,10,10a-hexahydrobenzo[c]chromen-1-ol | 316.485 |
This type of molecular information helps researchers recognise, examine and compare how HHC behaves in both testing and experimental work. Further research is needed to better understand how HHC interacts in different environments and applications.
How HHC is made
HHC occurs only in trace amounts in cannabis. Most commercial HHC is made in a laboratory by chemically converting CBD from hemp into THC-type compounds and then hydrogenating them (EUDA technical report, 2023). CBD itself is not intoxicating. Formula Swiss does not make or sell HHC.
Laboratories identify HHC with chromatography and mass spectrometry. The manufacture and handling of HHC are subject to national and international drug controls.
Effects and risks linked to HHC
HHC is a psychoactive cannabinoid with effects that can resemble those of THC. Human evidence now includes a small controlled-exposure study (Höfert et al., 2025) with psychophysical assessments, as well as clinical poisoning reports. Neither shows that HHC is safe long term.
A survey published in Cannabis and Cannabinoid Research noted that participants described experiences such as mood changes and a sense of relaxation. These findings are self-reported, not controlled clinical evidence.
The full range of possible risks and long-term outcomes related to HHC is still unclear. However, adverse reactions are not supported only by personal accounts: a retrospective French poison-centre study documented neurological, cardiovascular, gastrointestinal, psychiatric and ocular effects, including some serious cases. Limited analytical confirmation, possible co-exposures and selective reporting mean that the series cannot establish how frequently these outcomes occur among all users.
Clinical poisoning reports include neurological symptoms, gastrointestinal upset and cardiovascular effects. A small human exposure study also assessed psychoactive effects using psychophysical tests. The available studies remain limited and do not establish population-wide rates, long-term outcomes or the safety of a particular product.
Another important factor is that synthetic HHC can vary depending on the production method. These differences may affect consistency and could result in the presence of unintended by-products.
At present, knowledge about potential effects linked to long-term or repeated use of HHC is limited. Continued research is needed to gain a clearer picture of its characteristics and impact.
Known effects and risks of HHC use
| Reported effects | Potential risks |
|---|---|
| Psychoactive qualities similar to THC | Dizziness, digestive discomfort |
| Anecdotal comparisons to cannabis-related experiences | Variations in product consistency |
| Small human studies and clinical poisoning reports | Unclear long-term outcomes |
Since information about HHC is still emerging, it is important to remain cautious and stay informed through trusted updates and professional perspectives.
Potential dangers of HHC use
There are several risks associated with HHC that warrant caution. Habitual exposure to HHC and other cannabinoids may contribute to behavioural patterns that raise concern, particularly among younger individuals. Prolonged and frequent use could negatively affect cognitive and emotional balance.
Beyond these considerations, using HHC during pregnancy may carry added concerns. Since its effects on prenatal development have not been studied in depth, it is recommended to approach with caution if pregnant or planning pregnancy.
Some people have also pointed out psychosocial effects, including lower motivation and difficulties with focus, particularly when HHC is used often. These issues may influence work, relationships and overall day-to-day balance.
| Concern | Description |
|---|---|
| Potential behavioural dependence | Repeated exposure may encourage recurring patterns of use, which require further research. |
| Lung irritation risk | Inhaling vapour could pose risks to the lungs, especially if product quality is uncertain. |
| Pregnancy-related risks | There is little information on developmental outcomes, so use during pregnancy is discouraged. |
| Impact on focus and relationships | Frequent use may interfere with responsibilities at home or work, as well as personal connections. |
HHC products and availability
HHC products are sold as alternatives to THC products.
Such products are available through online stores, vape retailers and some speciality shops. Their increasing presence highlights the importance of reliable production standards and consistent quality control.
European drug monitoring has found HHC sold as vape cartridges, edibles, oils and hemp flower sprayed with HHC: low-THC hemp to which HHC has been added, which can be as intoxicating as cannabis despite its low THC content (EUDA, 2023).
Legal status (September 2026)
In March 2025 the UN Commission on Narcotic Drugs voted to add HHC to Schedule II of the 1971 Convention on Psychotropic Substances. The decision took effect on 6 December 2025, making HHC the first semi-synthetic cannabinoid under international control (UNODC). Many European countries had already banned it nationally.
Emerging research and monitoring of HHC
Human HHC research includes controlled-exposure pharmacokinetic and psychophysical work alongside observational toxicology reports. The small exposure study was not blinded or randomised, and poison-centre series have reporting and analytical-confirmation limitations. Larger, well-designed studies are needed to clarify its properties, interactions and longer-term risks.
The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has been observing HHC through its EU Early Warning System (EWS) since October 2022. This initiative collects information to evaluate potential concerns related to new substances like HHC.
As more results become available, stakeholders including regulators, health bodies and industry players will gain a stronger understanding of HHC’s role within cannabinoid research.
Frequently asked questions
What is HHC (hexahydrocannabinol)?
HHC is a hydrogenated derivative of THC: hydrogenation removes the one carbon–carbon double bond in THC’s cyclohexene ring. It is intoxicating and, since December 2025, under international drug control.
Is HHC found naturally in cannabis plants?
HHC is present in trace amounts in cannabis, typically in pollen and seeds. Most HHC used in products is synthesised through hydrogenation.
How is HHC different from THC?
HHC differs structurally from THC because its non-aromatic carbon–carbon double bond is saturated. HHC is often marketed as more stable than THC, but this has not been shown in comparative studies.
Is HHC psychoactive?
HHC is reported to interact with cannabinoid receptors in a manner similar to THC, although its effects may differ in intensity and duration.
What methods are used to produce HHC?
Hydrogenation is the most common method, involving the addition of hydrogen atoms to THC in the presence of a catalyst, such as palladium.
Can HHC be detected in drug tests?
Yes. Studies have shown that HHC and some of its metabolites can cross-react with certain THC screening tests and produce a positive result. Results depend on the test and sample. A screening result does not uniquely identify the cannabinoid; confirmation using appropriate mass spectrometric methods may be needed. See the study of HHC and cannabis screening tests.
What forms of HHC products are available?
European drug monitoring has documented HHC in vape pens, e-liquids and cartridges, as well as edibles, oils and treated hemp flowers or resin. Being on sale does not mean they are safe or legal. See the European monitoring report published in 2023.
How does HHC compare to other cannabinoids like delta-8 or delta-10 THC?
HHC differs chemically because of its hydrogenation. Like delta-8 THC, which acts as a weaker partial agonist at the CB1 receptor than delta-9 THC (Tagen and Klumpers, 2022), it is intoxicating, but its effects are distinct due to its structure.
Is HHC a synthetic cannabinoid?
HHC is considered semi-synthetic because, although it exists naturally in minimal quantities, commercial versions are produced through laboratory processes.
Is HHC legal?
Since 6 December 2025, HHC has been in Schedule II of the UN 1971 Convention on Psychotropic Substances, following a March 2025 vote of the Commission on Narcotic Drugs (UNODC). Many European countries had already banned it.
Which cannabinoids produce a psychoactive effect?
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Sources
- Höfert L et al. (2025). Preliminary pharmacokinetic and psychophysical investigations after controlled oral and inhalative consumption of hexahydrocannabinol (HHC). Scientific Reports. www.nature.com/articles/s41598-025-93931-4
- Ferretti ML et al. (2024). A Survey Study of Individuals Using Hexahydrocannabinol Cannabis Products: Use Patterns and Perceived Effects. Cannabis Cannabinoid Res. pubmed.ncbi.nlm.nih.gov/37934167/
- Labadie M et al. (2024). Hexahydrocannabinol poisoning reported to French poison centres. Clin Toxicol (Phila). pubmed.ncbi.nlm.nih.gov/38426845/
- UNODC Laboratory and Scientific Service (2025). CND decision on international control of hexahydrocannabinol (HHC) and carisoprodol enters into force. www.unodc.org/LSS/Announcement/Details/0c4632e4-ba34-4eef-96
- Helander A et al. (2024). Appearance of hexahydrocannabinols as recreational drugs and implications for cannabis drug testing - focus on HHC, HHC-P, HHC-O and HHC-H. Scand J Clin Lab Invest. pubmed.ncbi.nlm.nih.gov/38619215/
- Tagen M et al. (2022). Review of delta-8-tetrahydrocannabinol (Δ(8) -THC): Comparative pharmacology with Δ(9) -THC. Br J Pharmacol. pubmed.ncbi.nlm.nih.gov/35523678/
- European Union Drugs Agency (2023). New cannabinoid HHC in the spotlight as market evolves.
- EMCDDA (2023). Hexahydrocannabinol (HHC) and related substances: technical report.
- EMCDDA (2022). Technical expert meeting on hexahydrocannabinol (HHC) and related cannabinoids.
- European Union Drugs Agency. EU Early Warning System on new psychoactive substances.
