What is THCP? Tetrahydrocannabiphorol vs THC explained

THCP, short for tetrahydrocannabiphorol, is a cannabinoid first reported in a December 2019 research paper. The team found it in FM2, an Italian medicinal cannabis variety, alongside a CBD cousin called CBDP. THCP’s structure differs from THC in one way that matters: its side chain is seven carbons long instead of five. In a lab binding test, that longer tail let it grip the CB1 receptor about 33 times more tightly than THC.

That 33 is where the slogan “THCP is 33 times stronger than THC” comes from. It describes how tightly a molecule binds in a test tube, which is a different thing from how a person feels, and almost nothing about THCP has been tested in people.

Last reviewed: November 2026.

Tetrahydrocannabiphorol: what the 2019 discovery paper found

Cinzia Citti and colleagues described THCP in a Scientific Reports paper published December 30, 2019. They worked with FM2, a medicinal variety supplied by the Military Chemical Pharmaceutical Institute in Florence, separated out the new compounds, and confirmed their identity by making them synthetically for comparison. They proposed the names tetrahydrocannabiphorol and cannabidiphorol, following the naming convention for these molecules.

The paper also ran a standard behavioral test in mice and reported THC-like activity from THCP. That’s an animal result, and it doesn’t tell anyone what amount of THCP would do what to a person.

THCP vs THC: why a longer tail binds tighter

Most familiar cannabinoids, THC and CBD included, carry a five-carbon side chain. The 2019 paper notes that plants also make cousins with shorter chains: the varin family, such as THCV, has three carbons, and the authors had earlier reported a four-carbon butyl version, THCB. THCP extends the chain to seven.

In the binding test, a lower number means tighter grip. THCP came in at 1.2 nanomolar against 40 for THC, 15 for THCB and 75.4 for THCV, which means about 33 times higher binding affinity than THC and 63 times higher than THCV at the CB1 receptor in that assay. The paper calls it more “active,” but a binding constant measures grip, not what the molecule does once it’s bound. The authors’ modeling suggests the seven-carbon tail fills a channel in the receptor that THC’s shorter chain only partly occupies.

None of that converts into a dose. A molecule that binds tighter doesn’t mean one milligram of it equals 33 milligrams of THC in a person, and nobody has published a study that measured such a conversion.

THCP effects: what human reports show

Human evidence is thin. A 2025 clinical case report published in 2025 describes a person who developed severe psychosis and self-injury after taking THCP by mouth. The authors note the person had used THC products before, and the history included alcohol use and other factors. One case can’t tell you how common a reaction is, but it does show that being used to THC is no guarantee of a familiar experience with THCP.

The same report’s authors say only small amounts of THCP occur naturally in the plant, which is why it is isolated and also produced synthetically. A product’s front label rarely says which.

Is THCP legal in California?

Most THCP products have been sold online as hemp, and California has closed that door. The CDPH AB 8 FAQ says most of AB 8 took effect January 1, 2026, that the law generally treats intoxicating hemp products as cannabis, that inhalable hemp products containing hemp-derived THC can’t be sold in the state, and that hemp extract in food and drinks can’t contain THC or synthetic cannabinoids. The FAQ doesn’t name THCP, but a THCP gummy or vape marketed as hemp sits squarely in the category the law targets.

Inside the licensed market, products go through state testing and labeling. If you see an unfamiliar cannabinoid advertised anywhere, the safer question is whether it comes from a licensed retailer with a lab-tested label, and whether the label lists that cannabinoid at all. This is general information, not legal advice.

THCA vs THCP and other confusing names

THCA is the raw acid form of THC; a 2022 study of cannabinoid chemistry notes that plants store cannabinoids in acid form and heat converts them. THCP is a different molecule with a longer tail. A label’s THCA number says nothing about THCP. This article is about delta-9-THCP, the compound in the 2019 paper, and CBDP is its CBD counterpart. A product labeled THC-P or THCP doesn’t by itself tell you which isomer is inside or how much, so look for a lab-tested label that names the compound.

THCV and THCVA are the short-tailed relatives. Our THCVA guide explains that family, and the Learn hub covers the basics.

If anything you’ve taken causes a reaction that worries you, call California Poison Control at (800) 222-1222, the number DCC lists, or 911 in an emergency, and keep the package for responders. Never drive after using cannabis. Your local Vibe store can walk you through the cannabinoids listed on any licensed product’s label.

Frequently asked questions

Sources

• Citti et al., Scientific Reports, 2019
• Greer et al., Psychiatry and Clinical Neurosciences Reports, 2025
• CDPH: Assembly Bill 8 FAQ
• Kim et al., Plants, 2022: cannabinoid contents and biosynthetic genes
• DCC: responsible cannabis use

For adults 21+ (18+ with a physician’s recommendation in California). Keep out of reach of children and pets. Do not drive or operate machinery after use.