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THCO: What's the truth about it being a cannabinoid with psychedelic effects?

What is THCO?

THCO or tetrahydrocannabinol acetate is a (semi)synthetic cannabinoid, it is a derivative of THC (tetrahydrocannabinol, delta-9 THC). It is not present in even trace amounts in the cannabis plant and is the acetate form of the THC ester, which is formed by combining delta-8 or delta-9-THC with acetic anhydride.

An ester is a chemical compound that is formed in a process called esterification. A chemical reaction occurs between an acid and an alcohol to form an ester and split off the water (droplet). The structure of the ester is a carbon chain in which one oxygen atom links a carbon atom from the alcohol to a carbon atom from the acid.

In the case of THCO, the ester is usually formed from delta-8-THC and acetic anhydride. This ester is then much more potent than THC itself, meaning that it has potentially stronger psychoactive properties.

By the way, esters are all around us and are used e.g. as fragrances in perfumes or occur naturally in fruits. In industry, they are used as solvents or plasticizers to give flexibility to plastics.

Where did the reputation of the "psychedelic cannabinoid" THCO come from?

The first reports of the discovery of THCO date from 1949-1974 and are documented in U.S. Army studies during experiments at Edgewood Arsenal. During this time period, there were also references to recreational use of the substance, while the official argument for why the military studied the substance remains a secret from the public.

The chemist David Gold published a paper on the effects of this substance in 1975 and wrote in it, "Acetate is more spiritual and psychedelic than ordinary substances. The most striking characteristic is the 30-minute delay before the onset of effects."

Although this text has fallen into obscurity, it could be said to have laid the foundations for THCO's reputation. It was for its effects, which can range from hallucinations, that it earned the label of 'psychedelic cannabinoid'

High Times magazine, which has been a source of information on cannabis, culture, brands and marijuana legalization laws since 1974, said THCO is 3 times "more intoxicating" than THC and also called it a "psychedelic cannabinoid." Despite this figure being repeated in several articles on the internet, it is not backed up by official data. This information appears to have appeared in a 1977 book by Michael Starks, "Marijuana Chemistry: Genetics, Processing, Potency".

In 1978, THCO in Florida came to the attention of the DEA, which tracked down a secret lab in Jacksonville where a combination of cannabis extract and acetic anhydride was found. Since nothing major happened for the next 10 years, or the substance did not enter the illegal market, there was no further investigation by the DEA.

In 2023, the "psychedelic cannabinoid" moniker was debunked by research conducted by scientists at the University at Buffalo in New York. This research involved 300 THCO users and the researchers asked them to report the extent to which they felt various experiences, changes in time perception, pain relief, euphoria, hallucinations and paranoia.

Participants also administered items from the Mystical Experiences Questionnaire (MEQ), a common tool for assessing psychedelic experiences, and answered which psychedelics, such as LSD or psilocybin mushrooms, they had consumed.

Of those surveyed, 79% said THCO was not psychedelic or only mildly so. The survey result seems to indicate that THCO does not cause any psychedelic effect in most people.

THCO production

Acetate production is a process that involves a series of extractions and requires a professional laboratory environment - it is carried out in a technical laboratory with a vacuum fume hood. The process involves acetic anhydride, which is extremely flammable and potentially explosive.

At the origin of THCO is CBD (cannabidiol), which is extracted from the cannabis plant using one of the extraction methods, then CBD is converted to delta-9 or delta-8-THC.

As we have already discussed, acetic anhydride is used to synthesize THCO, which combines with delta-8 or delta-9 THC molecules. It is a highly flammable, colourless liquid that is also commonly used in the manufacture of plastics, pharmaceuticals, dyes, fibres and explosives.

During the secondary chemical reaction of the substances in question, the hydroxyl group of THC is replaced by an acetyl group to form THC acetate. This modification increases the solubility of the substance in fats and its permeability to membranes, which facilitates its absorption by the body. This change is believed to make it more potent than THC.

The final form of THCO resembles a thick brown liquid similar to motor oil. This distillate is used, for example, in vaping refills (liquids), tinctures and edibles.


Young scientists conduct research investigations in the lab, a researcher in the foreground uses a microscope in the THCO lab

Effects of THCO

At the moment, there is a lack of research to evaluate how THCO affects the body. There is a Content Analysis of Social Media Discussions on THC-O-Acetate, published in July 2023, which discusses individual user opinions on the effects, including onset and duration, consumption patterns and concerns about the compound. In this analysis, it appears that users:

  • most often compared THCO with delta-9-THC and delta-8-THC
  • reported a variety of effects, with some reporting experiences typical of THC
  • some reported mild or no psychedelic effects
  • for the most part reported relatively long onset of effects and/or long duration of effects
  • expressed concern about differences in the quality, composition and/or effect of products
  • several have specifically expressed safety concerns about ketene formation
  • described adverse experiences that included physical effects such as coughing and psychological effects such as anxiety

Anecdotal reports of THC acetate use vary widely. Some claim that it is slightly similar to a small dose of a psychedelic drug such as mushrooms (psilocybin) or LSD, while others claim that it has no psychedelic effects at all.

Based on the reports so far, it appears that the effects of THCO are in fact similar to those of delta-8-THC or THC, but probably about 3 times more intense than THC and about 6 times stronger than delta-8-THC.

THCO can affect perception, inducing strong feelings of euphoria and relaxation. Some users report that it has strong sedative properties. It is also reported to have spiritual effects.

THC acetate is exclusively suited for experienced users. Under no circumstances should one drive or operate any machinery after use.

How long does it take for THCO to take effect?

If THCO is vaped (inhaled) through vapes, pre-rolls or dab rigs, the effects start to appear in about 20 minutes. In the case of THCO oil, the effects appear in about 30 minutes and in edible form (edibles, gummies) it may take 1-2 hours for the effects to take effect.

It is important to note that the onset of effects is probably longer for THCO than for most other cannabinoids. For comparison, vape pens with cartridges containing CBD, CBN, CBG will experience effects in about 5 minutes after vaporization, similarly with the psychoactive cannabinoid THC, where effects usually appear in 3-5 minutes.

Why does THCO have a longer delay before it takes effect? This is because it is referred to as a "prodrug", meaning a substance that is activated only after it has been metabolized by the liver, so it takes longer to take effect. Once the THCO has been metabolised, it is de facto only the THC that is retained. The question then arises: why should it be stronger? There's a lot of speculation around this at the moment, with estimates that bioavailability plays a role.

The acetylated version of THC is said to be more bioavailable than the "classic" version. Once the acetate THC is absorbed, the unique functional group (-O) is removed and the THC starts to act as normal, but the effect is more intense, as if a higher dose of THC had been ingested.

Side effects of THCO

When taking these compounds, it is recommended that you be vigilant and watch out for any unexpected reactions. Think also that THCO has a later onset of effects, which can lead to an unintended overdose that may end in "bad trip". Therefore, always wait a sufficient period of time before deciding on the next dose.

There is also a natural risk of side effects associated with this type of substance. As with other cannabinoids with psychoactive properties, side effects such as:

  • dry mouth
  • red eyes
  • low blood pressure
  • increased heart rate
  • Sleepiness
  • Dizziness
  • Disorientation
  • changes in colour and brightness perception
  • negative psychological effects (panic, paranoia, anxiety and hallucinations)

The intensity of these effects will vary depending on the health status, metabolism and sensitivity of the user, the dose and the method of consumption. If severe or prolonged side effects occur, seek professional medical advice immediately.

To date, no animal or human research has been conducted to evaluate the safety of tetrahydrocannabinol acetate or any of the unknown by-products that result from the synthesis of this compound. There is also no research that has investigated the efficacy or safety of THCO for therapeutic purposes.

Risks associated with (semi)synthetic cannabinoids

The reality is that until THCO and other cannabis derivatives are regulated, consumers must weigh the potential risks and benefits of these compounds for themselves.

Experts are clear that natural cannabinoids are safe for medical and recreational use, unlike (semi)synthetic cannabinoids, which often cannot be proven to be pure and safe.

Unknown substances such as unnatural isomers, residual solvents and other unrecognised compounds have been found in some (semi)synthetically produced products, making them potentially dangerous for human consumption.

This issue is highlighted by cannabis researcher and chemist James Stephens, who noted in his work for cannabis product and brand consultancy Iron Light: "Currently, at the beginning of the commercial emergence of this compound, there is a wide variation in product quality."

Stephens periodically contacts THCO's manufacturer to send lab test results. He stated that he is concerned about the lack of specificity, i.e., the fact that the manufacturers themselves do not know what a certain percentage (10-15%) of the unknown substances in the product are.

Stephens told Leafly that smoking this molecule in a cartridge raises another set of questions, as combustion can trigger other chemical processes. "We just don't know [what will happen], but you can't run around saying any of this is safe."

Some research warns that acetate forms of the substances produce ketene, a chemical that can cause serious lung damage, when exposed to heat. It is therefore advisable to consider using it in the form of oils or edibles instead.

Comparison THCO vs. THCPO vs. HHCPO




Other designations

Tetrahydrocannabinol acetate


  • THC-O
  • THC-O-Acetate
  • THC acetate
  • ATHC


Other names are according to whether it comes from delta-8 or delta-9 THC:


  • delta 9/8-THC-O-acetate
  • delta 9/8 -THC-O

Tetrahydrocannabiphorol acetate


  • THCP-O

Hexahydrocannabiphorol (hexahydrocannabiphorol) acetate


  • HHCP-O

Molecular formula





A semi-synthetic cannabinoid not found in cannabis.

A semi-synthetic cannabinoid not found in cannabis.

A semi-synthetic cannabinoid not found in cannabis.


Acetate form of THC ester.

A modified form of the cannabinoid THCP, an alkyl chain consisting of 7 carbons.

It is reported that HHCPO is derived from HHCP (a derivative of HHC) or that the original precursor is a semi-synthetic derivative of THCP.

Production process

Acylation, acetic anhydride is used to synthesize THCO


Hydrogenation and acylation

Psychoactive effects




Legal status

It may find itself in a legal grey area, as of 17 June 2024 it is not on the list of banned substances in most countries. It is a banned compound in Sweden, the UK and Bulgaria.

It may find itself in a legal grey area, as of 10 June 2024 it is not on the list of banned substances in most countries. It is a banned substance in Bulgaria, Austria and the UK.

It may find itself in a legal grey area, as of 10 June 2024 it is not on the list of banned substances in most countries. It faces bans in Bulgaria, Lithuania and Latvia.

THCO products

Despite the availability of THCO products, there is still no research that focuses on the effects or how this compound works in the body.

In the markets, the most common are:

  • THCO oils combining THCO "extract" with carrier oils
  • Vapes: allow inhalation of THCO in vapour form. THCO vapes can be purchased as "disposables" (usually lasting about 200-800 puffs depending on the type of device, or vapes refillable with liquid or with replaceable cartridges).
  • THCO flowers: cannabis flowers infused with THCO distillate
  • Dabs: concentrated forms of cannabis (e.g. wax, shatter, crumble, butter, honeycomb, sugar, crystals), can be inhaled through vaporizers or dabbing.
  • Edibles (snacks, gummy candies)


Cannabis Oil Vial and Vape Pen - New THCO Products


THCO is a (semi)synthetic cannabinoid, it is the acetate form of the THC ester, which is formed by chemical reaction from delta-8-THC or delta-9-THC compounds and acetic anhydride. Production requires a professional technical laboratory.

Incidentally, other examples of (semi)synthetic cannabinoids include THCB, HHCH, HHCPO, HHC, HHCP, THCJD, THCP, THCH and others.

Tetrahydrocannabinol Acetate can affect perception, inducing strong feelings of euphoria and relaxation. In the most recent 2023 survey, 79% of respondents said THCO was not psychedelic or only mildly so.

THC acetate is a 'prodrug', meaning that the substance is activated only after it has been metabolised by the liver. It takes at least 20-30 minutes for the effects of THCO to take effect.

Remember that compounds of this type can be much more potent than natural cannabinoids, and this increases the potential risk of overdose and intoxication.

When purchasing any cannabis products, always choose trusted and reputable companies that have their products tested by an independent laboratory.


Author: Canatura



Photo: Shutterstock

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