THCP: 33 times THC's affinity, banned in France since 2024

THCP is a phytocannabinoid, a molecule the cannabis plant makes itself. An Italian team led by Cinzia Citti and Giuseppe Cannazza (University of Modena and Reggio Emilia, CNR Nanotec in Lecce) isolated and described it in Scientific Reports on 30 December 2019. The team was studying FM2, a medical cannabis variety grown in Italy, and its paper also describes CBDP, the long-chain counterpart of CBD.

Its core is that of Δ⁹-THC. The two differ only in the side chain, a tail of carbon atoms attached to the core, which has 7 carbons in THCP (a heptyl group) and 5 in THC (a pentyl group). The suffix "phorol" comes from sphaerophorol, the common name of the heptyl resorcinol that makes up this part of the molecule.

Keep it apart from THCPO, which is THCP made into an ester by synthesis, and from HHCP, its hydrogenated version.

To measure how THCP binds cannabinoid receptors, the 2019 team used a constant called Ki: the lower it is, the more tightly the molecule holds the receptor. THCP has a Ki of 1.2 nM at CB1 and 6.2 nM at CB2, compared with 40 nM for THC at CB1. The authors read this as an affinity about 33 times stronger.

Injected into mice at 2.5 to 10 mg/kg, THCP produced the four standard signs of THC-like activity: less movement, immobility, a drop in body temperature and a reduced response to pain. These are animal results, obtained with injected doses.

No controlled trial exists in humans, only isolated reports. In 2025, a New Jersey team published the case of a man admitted to hospital after taking 8 mg of THCP. A regular THC user with no history of psychosis, he had psychotic symptoms for 48 hours and injured himself. A single case cannot establish an average risk, but it shows that a high affinity in the lab deserves to be taken seriously.

An American study from 2021 measured THCP in 14 plants from six chemotypes, or chemical profiles. All 13 flower samples from THC-dominant varieties contained it, at 0.0023% to 0.0136% by weight, and none was detected in the CBD-dominant variety. At 0.01%, it would take 10 kg of flowers to extract 1 g of THCP.

Extraction therefore cannot explain the THCP sold between 2021 and 2024. A German police laboratory analysed 79 samples seized in Rhineland-Palatinate between December 2021 and December 2023, all flowers and resins containing semi-synthetic cannabinoids. Δ⁹-THCP turned up in 47.5% of them, nearly always with its Δ⁸ isomer. The authors see this pairing as a sign of chemical synthesis, by acid-catalysed cyclisation of a long-chain CBD analogue.

A hemp flower with a measurable amount of THCP has very probably been treated with a synthetic product. HHC is produced the same way, as our timeline of the HHC ban shows.

In a decision of 22 May 2024, effective 3 June 2024, the ANSM added new cannabinoids to the list of narcotics. It covers any substance derived from the benzo[c]chromene core with certain substitutions, an alkyl chain at position 3 among them, and the ANSM names THCP as one of the molecules concerned. One year before, it had classified HHC, HHCO and HHCP from 13 June 2023.

Once a molecule is classified, narcotics penalties apply. Under article L3421-1 of the Public Health Code, using a narcotic carries one year in prison and a €3,750 fine, with a fixed fine of €500. Transport, possession, supply, transfer and purchase come under article 222-37 of the Criminal Code, with up to 10 years in prison and a €7,500,000 fine.

A correction about THCA: the previous version of this article listed it among the banned molecules, which is wrong for compliant hemp. The amendment of 3 June 2024 excludes it when the THC content stays within the 0.30% threshold. Our article on THCA gives the details.

On packaging, look out for THCP, THC-P, Δ⁹-THCP, Δ⁸-THCP, THCPO and HHCP. Wording like "enhanced effect", "new generation" or "stronger than CBD" on a supposedly "hemp" product is another warning sign.

A certificate of analysis needs three checks:

1. the batch number matches the product on sale;
2. THCP appears in the list of cannabinoids tested, since a laboratory that never searched for it cannot say it is absent;
3. THCP and HHC read "not detected" (or "< LOQ", below the limit of quantification), and Δ⁹-THC is at 0.30% or less.

Each line is explained in our guide to reading a certificate of analysis, and the laboratory page describes the measurement methods. The risk is real. In June 2025, the ANSM and Anses reported several hundred poisonings since early 2024 among users of products sold as containing CBD, most often involving undeclared THC or synthetic cannabinoids. The warning signs are listed in our advice on avoiding synthetic cannabinoids.