In Czech shops, it is not difficult to come across “legal” cannabis substitutes. These may take the form of pre-rolled joints, vape pens, cannabis trim, hashish, various extracts, or even sweets. Their manufacturers promise effects similar to classic cannabis and try to attract customers with the fact that their goods are freely available. In reality, science still knows very little about many of these substances, and they can seriously endanger consumers’ health and lives. Where did synthetic cannabis substitutes come from, and what risks do they involve?
The effects of cannabis are due to cannabinoids, terpenophenolic compounds that plants produce and store in glands (trichomes) on the surface of flowers and leaves. More than 150 cannabinoids have been discovered in cannabis so far, with tetrahydrocannabinol (THC) and cannabidiol (CBD) occurring in the greatest amounts in the plants. While THC is psychoactive and responsible for a large part of cannabis’s intoxicating effects, CBD has calming and anti-inflammatory effects. The other cannabinoids in cannabis are referred to as minor cannabinoids and occur in much smaller concentrations, although many of them are being studied for their potentially medicinal effects.
Where cannabis substitutes come from and what the risks of using them are
Cannabinoids do not have to be produced only in plants. Various variants can be made in the laboratory, either by transforming natural cannabinoids (for example legal CBD) or completely synthetically. Some of the cannabinoids obtained in this way occur in cannabis (usually only in trace amounts), while others are completely new and are often not on the list of prohibited substances. These are precisely the most interesting for manufacturers of legal cannabis substitutes, because they can bring them to market without facing any penalty. From the user’s point of view, however, the problem is that these substances are usually nowhere near as well researched as THC and other naturally occurring cannabinoids.
The risks of using synthetic cannabis substitutes can often only be estimated. The effects of cannabinoids on the human body are possible thanks to receptors of the endocannabinoid system, which is part of the nervous system. These receptors (CB1 and CB2) are distributed throughout the body, but most of them are found in the brain and spinal cord (CB1) and in immune system cells (CB2). Some cannabis substitutes such as THCP have up to 30× greater binding affinity for ECS receptors than THC, and therefore act for much longer and are significantly more potent. Users of substitutes therefore face a high risk of overdose, and although classic cannabis is considered safe in this respect, with such potent substances injury with serious consequences or even death can easily occur.
Another undeniable risk of cannabis substitutes is that quality control on the manufacturer’s side is almost non-existent. Laboratory tests of seized products repeatedly show that the substance content in many cases does not correspond to the description on the packaging. Manufacturers and sellers of cannabis substitutes also protect themselves by labelling their products as “collectables” that are not intended for consumption. Although this in no way protects them from legal penalties, the buyer can hardly expect serious treatment if problems arise.
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The most common cannabis substitutes, their effects and risks
The following list includes the most common synthetic cannabinoids that you may currently come across in shops or online. However, by the time you read these lines, some of these substances have probably already been banned and disappeared from the market. It can nevertheless be expected that profit-hungry sellers of cannabis substitutes will quickly replace them with new molecules that you will not find on our list or on any other list. The risks of using them are, however, the same or possibly even more serious than those of the substances described below. HiSeeds strongly warns against the consumption of synthetic cannabinoids of any kind or origin.
Risks of consuming synthetic cannabinoids
- Unknown effects and impacts on the human body.
- Interactions with medicines or other substances.
- Incorrect labelling or substance mix-ups.
- Toxic residues from production or formed during consumption.
- EVALI – serious and permanent lung damage caused by vaping.
- Strong potential for developing dependence.
Hexahydrocannabinol (HHC)
One of the most popular synthetically obtained cannabinoids of recent years, which was recently added to the list of prohibited substances. HHC was first synthesised by chemists Adams and Todd as early as the 1940s, during experiments with the hydrogenation of THC. Hexahydrocannabinol in modern substitutes is produced from CBD obtained from industrial hemp plants, usually in large foreign laboratories. Users describe the effects of HHC as comparable to THC.
Risks: The pharmacology and metabolism of HHC are very poorly researched, and the long-term effects of use on the human body are unknown.
10‑Hydroxy‑hexahydrocannabinol (10‑OH‑HHC)
A metabolite of HHC originally isolated from cannabis in the 1980s, which can be synthesised from CBD in a similar way to HHC. 10‑OH‑HHC is attributed effects similar to HHC, but with a shorter duration.
Risks: As with HHC, the risks and pharmacology of this substance are almost unexplored.
Δ9-tetrahydrocannabiphorol (Δ9-THCP)
THCP was first discovered in cannabis in 2019 and quickly attracted scientists’ attention because of its potency. It was found that THCP’s binding affinity to CB1 receptors is up to 33× higher than that of THC, which means that the substance is very potent and its effects may last for a long time. THCP can be obtained fully synthetically and in many countries it does not appear on the list of prohibited substances, which makes the molecule an ideal target for cannabis substitute traders.
Risks: The strong and long-lasting effects make THCP a particularly dangerous cannabinoid. According to user experience, the effects of THCP can last for more than 24 hours and are very intense. There is therefore a high risk of dependence and serious side effects with THCP.
Hexahydrocannabutol (HHCB)
No information is available on the synthesis of hexahydrocannabutol (HHCB), but it can be assumed that it is formed by hydrogenation of either Δ8-THCB or Δ9-THCB, i.e. fully synthetically. Anecdotal descriptions of the effects of edibles containing HHCB can be found on Reddit. Notable is the description of a rapid onset and short duration (5 to 15 minutes).
Risks: These have not yet been described in detail. General warnings apply.
Hexahydrocannabihexol (HHCH)
As with HHCO, there is not much in the scientific literature about the synthesis of HHCH. Users on Reddit describe that vaporising HHCH produces milder effects than oral consumption, for example in the form of sweets or other edibles, where the effects are described as very strong.
Risks: These have not yet been described in detail. General warnings apply.
Hexahydrocannabiphorol (HHCP)
HHCP was already tested in the 1940s and 1950s, and this cannabinoid can be obtained both fully synthetically and probably also by hydrogenation of cannabis extract. We do not yet know much about the effects of HHCP, but comments on internet forums describe exceptionally intense effects.
Risks: These have not yet been described in detail. General warnings apply.
Tetrahydrocannabinol acetate (THC-O)
Acetates of various THC isomers have been known since the 1940s. Today, we most often encounter acetates of Δ8-THC and Δ9-THC made from CBD obtained from industrial hemp. According to pharmacological studies, THC acetates act similarly to the non-acid forms of cannabinoids, but at lower doses (0.5–0.9 mg/kg for Δ8-THC and 0.1–0.25 mg/kg for Δ9-THC). The onset of effects is slower and they last longer.
Risks: As with cannabinol acetate (CBN-O), CBD diacetate (CBD-di-O) or hexahydrocannabinol acetate (HHC-O), vaping or dabbing products containing Δ9-THC-O may increase the risk of EVALI (e-cigarette or vaping-associated lung injury), i.e. acute lung damage associated with the use of electronic cigarettes.
Hexahydrocannabinol acetate (HHC-O)
Hexahydrocannabinol acetate (HHCO or HHC-O) was first mentioned in the scientific literature in 1942. The pharmacology of HHC acetate has not yet been researched, and on user forums its effects are often described as “1.5× stronger than HHC”. Users mention a slow onset of effects and rapid development of tolerance. Negative experiences after consuming edibles with HHC-O are common, followed by depressive mood persisting for several weeks.
Risk: In addition to the usual risks of cannabis substitutes, HHC-O is associated with the risk of EVALI, i.e. acute lung damage associated with vaping, because heating may produce the toxic gas ketene.
8-Hydroxy-hexahydrocannabinol (8-OH-HHC)
Unlike its regioisomer 10-OH-HHC, 8-OH-HHC has never been described as a naturally occurring cannabinoid. Users on internet forums state that the effects of 8-OH-HHC begin more quickly than with ordinary HHC. However, according to their experience, the course of the effects is very similar.
Risks: These have not yet been described in detail. General warnings apply.
HU-210 (Spice, K2)
The synthetic compound known as HU-210, specifically the (−)-1.1-dimethylheptyl (DMH) homologue of 11-hydroxy-Δ8-THC, was identified in 2009 in seized products labelled Spice Gold, Spice Silver and Spice Diamond by the United States Customs and Border Protection. HU-210 was originally synthesised in Raphael Mechoulam’s laboratory and shows exceptionally high potency – its affinity for the CB1 receptor is approximately seven times higher.
Risks: Fully synthetic cannabinoids such as HU-210 and others have in the past been associated with the synthetic cannabis epidemic at the beginning of the millennium. Many users of synthetic cannabinoids have died after consuming them, become dependent, or are dealing with serious health consequences. These substances can be extremely dangerous, and consuming them can end in serious health consequences.
Warning: This article is for informational and educational purposes only. Its aim is to raise awareness of synthetic cannabinoids, their properties and the possible risks associated with their use. The information provided in the article does not replace professional medical care, an individual assessment of health status, or the advice of a qualified healthcare professional. At HiSeeds, we care about a safe and responsible approach to cannabis and do not support the use of unverified synthetic cannabinoids or products of unclear origin.
Sources: Caprari C, Ferri E, Vandelli MA, Citti C, Cannazza G. An emerging trend in Novel Psychoactive Substances (NPSs): designer THC. J Cannabis Res. 2024 May 3;6(1):21. doi: 10.1186/s42238-024-00226-y. Erratum in: J Cannabis Res. 2025 Jan 6;7(1):2. doi: 10.1186/s42238-024-00254-8. PMID: 38702834; PMCID: PMC11067227.