What is HHC? Effects, risks and legality

HHC (hexahydrocannabinol) is a semi-synthetic cannabinoid with a psychoactive effect, derived from THC, that became popular as a “legal high”. But since 23 April 2025 HHC has been illegal in Spain. Here we explain what it is, how it is produced, what effects and risks it has, and its current legal status.

The world of cannabinoids includes a vast number of compounds that have not yet been fully described, identified or regulated. One of them is HHC or hexahydrocannabinol: a novel cannabinoid with a psychoactive effect that is already controlled and banned in many countries (in Spain, since April 2025). The popular HHC buds are CBD flower sprayed with this product to produce a psychoactive effect.

In this post we explain what HHC is and the crucial things you should know before jumping on the new craze sparked by this cannabinoid, advertised as “the legal high”, whose popularity kept growing until it was banned. You will discover that HHC products differ in composition and effects depending on the type of HHC they contain, and we will also look at their possible risks and legal status. Stay with us until the end!

What is HHC?

Hexahydrocannabinol (HHC) is a little-studied type of cannabinoid with a psychoactive effect that is found in very small amounts in cannabis (1) and produces an effect similar to tetrahydrocannabinol (THC).

In fact, HHC is found in the cannabis plant not because the plant produces it, but because it is a breakdown product of THC. THC is the best-known psychoactive cannabinoid to date and shares many of its characteristics with HHC.

Origin of HHC

HHC was first identified in 1940 (2) and is produced commercially by semi-synthetic means, that is, it is synthesised from THC and cannabidiol (CBD).

What CBD is and what it is used for: learn with our blog

There are no natural HHC products: it is made in laboratories and added to products, whether sprayed onto CBD flower, mixed with hash or included in oils and edibles.

Because HHC is found in very low amounts in cannabis, all the HHC on the market is obtained semi-synthetically, from THC or CBD, in a patented laboratory process.

HHC synthesis is a subject surrounded by misinformation and secrecy on the part of manufacturers. There is a basic process called hydrogenation, which produces a dark golden oil, known as hydrogenated cannabis oil (HCO), which is rich in HHC.

Products containing HHC

HHC products were detected on the European market in 2022. They were sold as a “legal” cannabis product, either as a replacement for THC or simply sprayed onto CBD flower or added to CBD hash to boost the psychoactive effects.

There is a wide range of hexahydrocannabinol products: HHC vapes, HHC oil to be dosed in drops, HHC weed, HHC hash and even edibles, such as cannabis sweets. These products claimed the title of “legal cannabis” products and, in general, contain a mixture of two types of HHC (the two isomers 9S-HHC and 9R-HHC).

Types of HHC

When we talk about HHC, we are actually referring to two hexahydrocannabinol compounds, whose short chemical names are (3):

• 9 alpha HHC (9α-HHC) for the (9S)-HHC epimer
• 9 beta HHC (9β-HHC) for the (9R)-HHC epimer, also known as hexahydrocannabinol (HHC), hexahydro-CBN or HXC

Epimers are different molecules with the same chemical composition but a different spatial structure (a type of isomer or stereoisomer), which influences their properties and effects. Depending on the type of synthesis, the final product will contain a higher proportion of one type of HHC or the other (9, 10).

The potency of HHC products depends on the dose and the type of HHC they contain. The 9R-HHC epimer has stronger psychoactive effects. The HHC on the market is a mixture of both types of molecule, which can lead to variations in the potency and overall effects that users experience with HHC products.

The 9R-HHC epimer has a higher affinity for endocannabinoid receptors, which means it is better able to bind to these receptors (4). As a result, 9R-HHC has more potent psychoactive effects than the other epimer.

By contrast, the 9α-HHC epimer (9S-HHC), because of its slightly different molecular structure, does not bind as actively to the body's natural endocannabinoid receptors as 9R-HHC. It is therefore considered to have much lower potency and little psychoactive effect. For simplicity, some people refer to these molecules as “active HHC” (for 9R-HHC) and “inactive HHC” (for 9S-HHC), purely colloquially (9).

What effects does HHC have on the human body?

HHC is a cannabinoid and therefore interacts with the endocannabinoid system to exert its effects on the body. Although there are no specific studies on HHC, it is said to bind to the same cannabinoid receptors as THC, which has a greater affinity for CB1 receptors, hence its psychoactive response.

Non-clinical studies and anecdotal reports indicate that HHC has psychoactive properties similar to THC, although with slightly lower potency (10).

Although the exact effects of HHC on the body are not known, the effects of THC are:

• Euphoria
• Relaxation
• Cognitive changes: altered perception of time and space, memory and ability to concentrate.
• Changes in sensory perception, such as more vivid colours or greater sensitivity to visual or auditory stimuli.
• Increased appetite (known as the “munchies”)
• Poor motor coordination
• Dry mouth (“cottonmouth”)
• Red, glassy-looking eyes

How HHC works in the body

Although little research has been done on HHC so far, some scientific articles mention that, for guidance only, it should be assumed to act in a similar way to THC. It is therefore assumed to be metabolised by the liver and to bind to the endocannabinoid system in a similar way to THC, resulting in a psychoactive effect. For a broader picture, you may want to take a look at our post on the effects of THC.

Differences between THC and HHC

THC and HHC are both cannabinoids found naturally in cannabis, but they differ in important ways in terms of their origin, effects and risks. Find out more in the post.

Differences between HHC and THC: is HHC an alternative to THC?

Therapeutic potential of HHC? Areas of research

It is curious that HHC was described in 1940 and yet there is little scientific information on its characteristics and physiological effects, so the correct or safe dose of HHC is not known. This is probably because its low presence in the cannabis plant made it seem less important than CBD and THC.

At present, there are no data to support the claim that HHC has any therapeutic effect.

Even so, some publications mention the anti-cancer effect of HHC analogues called LYR-7 and LYR-8 (5, 6), but these are results that we cannot extrapolate to humans.

Side effects and potential risks of HHC

The side effects and potential risks of HHC are not yet fully understood due to a lack of thorough research. However, it is believed that HHC, being a cannabinoid with properties similar to THC, could carry risks similar to those associated with THC use.

For example, regular use of THC or HHC, which constantly interact with the CB1 receptor, can disrupt the neuronal communication carried out by our endocannabinoids (7). By affecting neural circuits, this can give rise to the following adverse effects:

• Memory problems
• Developing anxiety
• Depression
• Paranoia

This is suggested by what is currently known about the long-term effects of THC use.

Precautions when using HHC

The cannabis industry is constantly on the move. The discovery of new cannabinoids leads to the rapid commercialisation of products that sit in a legal “limbo”, as was the case with HHC until it was banned. Because the long-term effects of HHC have not yet been documented, it is important to use it with caution.

Bear in mind that there are no natural HHC products: they are products that have been enriched with the semi-synthetic compound. HHC may be a cheaper alternative to using natural products derived from cannabis. Because of their lower cost, and because for years they were sold without regulation, synthetic or semi-synthetic cannabinoids tend to push natural cannabis compounds off the shelves in shops.

Something crucial needs to be highlighted here: the cannabis plant contains a wide range of compounds that interact synergistically with one another, known as the cannabis entourage effect. Science has tried to explain how some of these interactions work, but has not managed to fully clarify how the different compounds in cannabis can regulate the effects to maintain the balance, or homeostasis, of the human body. For example, CBD modulates the effect of THC, which suggests that the plant itself is “naturally” formulated to produce a balanced effect. This level of natural sophistication cannot be recreated in the laboratory and, therefore, caution should be taken when using compounds such as HHC.

The concerns surrounding a new compound such as HHC include not only the legal framework but, above all, the risks linked to the lack of research on its toxicity and safety profile. In an ideal world, using HHC or other synthetic cannabinoids would be like taking pharmaceutical products with controlled effects. But let's not forget that cannabinoids are unusual compounds whose effects vary from person to person, and negative individual traits (such as a predisposition to depression, stress or anxiety) can cause unwanted effects (8).

In the end, much of what is said about HHC is speculation; perhaps in the future science will point to some tangible benefit that justifies its mass production. For now, we recommend that you exercise caution and consult your doctor for more information.

HHC legality in Spain and Europe

The legal status of HHC has changed completely. When it burst onto the European market in 2022, it was sold by exploiting a legal loophole, but most countries have since banned it. HHC is now illegal in Spain: Order SND/380/2025, in force since 23 April 2025, added HHC and its derivatives (HHC-O, HHC-P, THCP, among others) to the list of controlled psychotropic substances. At Cannactiva we do not recommend buying HHC or other semi-synthetic cannabinoids: they are synthetic in origin with dubious traceability, and serious cases have been reported. If you are still considering it, check the law in your country very carefully, because it is dangerous.

At European and international level, the list of bans has kept growing:

• Austria — March 2023
• France — June 2023
• Italy, the United Kingdom, Belgium, Denmark, Switzerland… — 2023-2024
• Germany — June 2024
• Spain — April 2025
• UN — March 2025: HHC was added to Schedule II of the 1971 Convention on Psychotropic Substances.

Its sale, possession and use are therefore banned on the same terms as THC. If you are thinking of travelling with cannabis products, check the law at your destination first — with HHC, it is simply not a good idea.

The legal, natural and well-studied alternative is still CBD. We explain the differences between CBD and HHC and, if you are worried about being tested, whether HHC shows up on a drug test.

THC saliva test: what to do if you test positive

We hope you have found this information about the synthetic cannabinoid HHC, which made such a big splash in the CBD sector, useful. If you prefer the natural option, at Cannactiva you will always find the highest quality:

Note: this is an informational article and is not intended to prevent, diagnose or treat any disease. Its content may complement, but never replace, the diagnosis or treatment of any disease or symptom. Consult your doctor if you have any questions about using HHC.