9-OH-HHC.9-Hydroxy-hexahydrocannabinol

9-OH-HHC is a hexahydrocannabinol carrying a tertiary alcohol at position 9, in two epimeric forms, 9α and 9β. Garrett et al. identified it in 1978 among the acid degradation products of Δ9-THC; it also forms from CBD in artificial gastric juice (Watanabe et al., 2007) and is among the by-products of the acid conversion of CBD into Δ8-THC (EMCDDA 2023). Radwan et al. isolated its two epimers from a commercial Δ8-THC distillate in 2023, and it was first detected in Europe in December 2022 (ACMD 2025). Reggio et al. synthesised it in 1991 in an attempt to separate analgesia from psychoactivity: in mice, its two epimers were 10 to 25 times less potent than Δ9-THC in all tests, including antinociception, which modelling attributes to unfavourable conformations. In mice, 9α-OH-HHC produced catalepsy (ED50 of 8.0 mg/kg intravenously), less potently than Δ9-THC (Watanabe et al., 2007). No affinity constant for cannabinoid receptors, no pharmacokinetic data and no human study were found. The UK ACMD recommended in May 2025 that it be listed by name in Class B.

Source

Ahmed and colleagues isolated 9α-hydroxyhexahydrocannabinol in 2015 from a high-potency Cannabis sativa variety, among nine minor oxygenated cannabinoids. 9-OH-HHC also forms as a by-product of the chemical cyclisation routes used to prepare Δ8-THC and HHC. Radwan and colleagues isolated it in 2023 in its two epimeric forms, 9α and 9β, from a commercially sold Δ8-THC distillate. It also figures among the degradation products of Δ9-THC described as early as 1978, and among the compounds formed from CBD in artificial gastric medium.

No enzymatic pathway is described: the 9α form has been isolated from cannabis among minor oxygenated cannabinoids, with no established mechanism of formation in the plant. Outside the plant, the molecule results from a hydroxylation at position 9 on a hexahydrocannabinol skeleton, obtained chemically during the acid cyclisation of CBD or the reduction of Δ9-THC, and recovered as an impurity rather than as an intended product.

European Union

No control measure specific to the European Union targets 9-OH-HHC: it has been the subject neither of a risk assessment nor of a classification decision at European level, and the situation therefore depends on each Member State. The molecule figures among the related substances recorded in the technical report devoted in 2023 by the EMCDDA, now the EUDA, to HHC and related substances, which places it within the scope of the early warning system without amounting to classification. Outside the European Union, the United Kingdom's advisory committee, the ACMD, recommended in May 2025 that it be controlled in class B, schedule 1. It is listed in no schedule of the United Nations conventions.

France

9-OH-HHC is named in no French text. It does, however, fall under the generic clause added to annex IV of the decree of 22 February 1990 by the ANSM decision of 22 May 2024, which came into force on 3 June 2024: this clause covers any substance derived from the benzo[c]chromene nucleus, hydrogenated or not on ring A, bearing in particular a hydroxyl at position 1, an alkyl chain at position 3, one or two alkyl groups at position 6 and an alkyl substituent at position 9. 9-OH-HHC answers this description, save that the hydroxyl at carbon 9 does not appear literally in the enumeration of substituents admitted for that position, which leaves a margin of interpretation. The situation is therefore one of prohibition by generic clause, and not by listing by name as for HHC, scheduled by name since 13 June 2023. HHC has been listed in annex III of the decree since the ANSM decision of 16 January 2026.

Sources: EUR-Lex, UNODC, CND, ANSM, IUPHAR/BPS, ChEBI, EUDA. Our method.

Family

Semi-synthetic cannabinoid › Isomer or by-product

Chemistry

C5 side chain · neutral form

Natural trace reported

The 9α form was isolated from a very high-THC cannabis variety, among minor oxygenated cannabinoids (Ahmed et al. 2015).

Ahmed SA et al. Minor oxygenated cannabinoids from high potency Cannabis sativa L. Phytochemistry, 2015 (new tab)

Verification

Every fact on this entry was checked against its primary sources on 20 October 2026.

Wikipedia (English)

9-Hydroxyhexahydrocannabinol (new tab)

Article paired by the molecule's structure (InChIKey), revision read on 19 October 2026. Read as a second opinion, never cited as a source.

1. 1Garrett ER, Gouyette AJ, Roseboom H. Stability of tetrahydrocannabinols II. J Pharm Sci, 1978 (identification of 9-hydroxyhexahydrocannabinol among the degradation products of Δ9-THC) (new tab)PMID 22740
2. 2Reggio PH, McGaughey GB, Odear DF, Seltzman HH, Compton DR, Martin BR. A rational search for the separation of psychoactivity and analgesia in cannabinoids. Pharmacol Biochem Behav, 1991 (synthesis of 9β-OH-HHC, epimers markedly less active than Δ9-THC in mice) (new tab)PMID 1806940
3. 3Ahmed SA, Ross SA, Slade D, Radwan MM, Khan IA, ElSohly MA. Minor oxygenated cannabinoids from high potency Cannabis sativa L. Phytochemistry, 2015 (isolation of 9α-hydroxyhexahydrocannabinol) (new tab)PMID 26093324
4. 4Radwan MM, Wanas AS, Gul W, Ibrahim EA, ElSohly MA. Isolation and Characterization of Impurities in Commercially Marketed Δ8-THC Products. J Nat Prod, 2023 (isolation of 9β-OH-HHC and 9α-OH-HHC from a commercial distillate) (new tab)PMID 36827690
5. 5Watanabe K, Itokawa Y, Yamaori S, Funahashi T, Kimura T, Kaji T, Usami N, Yamamoto I. Conversion of cannabidiol to Δ9-tetrahydrocannabinol and related cannabinoids in artificial gastric juice, and their pharmacological effects in mice. Forensic Toxicology, 2007 (new tab)DOI 10.1007/s11419-007-0021-y
6. 6Schirmer W, Walton SE, Weinmann W, Schürch S, Logan BK, Krotulski AJ. Rapid LC-QTOF-MS screening method for semi-synthetic cannabinoids in whole blood. J Anal Toxicol, 2026 (validated method including 9α-OH-HHC and 9β-OH-HHC reference standards) (new tab)PMID 41117773
7. 7ANSM. Decision of 22/05/2024 amending the list of substances classified as narcotics (generic benzo[c]chromene clause added to annex IV of the Order of 22 February 1990) (new tab)
8. 8ANSM. Decision of 03/06/2024 amending the list of substances classified as narcotics (CBNA, THCV, THCVA, THCA exclusions) (new tab)
9. 9ANSM. ANSM places hexahydrocannabinol (HHC) and two of its derivatives on the list of narcotics, 12 June 2023 (HHC, HHCO, HHCP classified by name from 13 June 2023) (new tab)
10. 10ANSM. Decision of 16/01/2026 amending the list of substances classified as narcotics (HHC listed in annex III) (new tab)
11. 11EMCDDA (EUDA). Hexahydrocannabinol (HHC) and related substances, technical report, 2023 (9-OH-HHC is listed there among the related substances catalogued) (new tab)
12. 12ACMD (UK). Semi-synthetic cannabinoids: cannabinoids related to tetrahydrocannabinol and cannabidiol, advice letter, May 2025 (Class B control, Schedule 1, recommended for 9-OH-HHC) (new tab)
13. 13Abdel-Kader MS, Radwan MM, Metwaly AM, et al. Chemistry and Pharmacology of Delta-8-Tetrahydrocannabinol. Molecules, 2024 (9β-OH-HHC and 9α-OH-HHC described as impurities of Δ8-THC products) (new tab)DOI 10.3390/molecules29061249
14. 14Docampo-Palacios ML, et al. Saturated Cannabinoids: Update on Synthesis Strategies and Biological Studies of These Emerging Cannabinoid Analogs. Molecules, 2023 (new tab)DOI 10.3390/molecules28176434
15. 15PubChem CID 71579182, (6aR,10aR)-6,6,9-trimethyl-3-pentyl-7,8,10,10a-tetrahydro-6aH-benzo[c]chromene-1,9-diol (new tab)

SMILES

CCCCCC1=CC(=C2[C@@H]3CC(CC[C@H]3C(OC2=C1)(C)C)(C)O)O

Machine-readable entry (JSON)

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