Cannabis is a rich, complex plant that has a broad diversity of psychoactive compounds. But not all of its psychoactive compounds have psychotropic effects; to put it another way, not all of them make you “high”. This is something that people are starting to understand with the popularisation of CBD (cannabidiol). THC (tetrahydrocannabinol), among other things, makes you “high”; CBD doesn’t. This is also the case with terpenes. These are psychoactive compounds that do not make you “high”, but they do interfere with what does make you “high”. How much do terpenes interfere with the effect of cannabis? Can it be said that if the terpenes in cannabis were known, its effects could be predicted?
Although terms such as terpene profile or terpene map are starting to become quite commonplace in cannabis circles, the fact is that terpenes weren’t discovered by cannabis connoisseurs. Used in the food industry as odorants and flavourings, and also in the perfume and cosmetics industry, terpenes have long been known to mankind. In a rather undercover manner, they have been widely used in traditional or popular medicine. Lavender is well-known for its sedative and anxiolytic properties, thanks to its high linalool content. And what about the anti-inflammatory properties of clove, attributable to eugenol, or the expectorant properties of eucalyptus, thanks to the presence of eucalyptol, to mention just a few examples? We now know that terpenes make up the majority of the components of the essential oils, those “household” remedies that have alleviated so many ailments and which have been known since time immemorial.
In cannabis, as in the other plants, the terpenes are the components that are responsible for their characteristic smell and taste. When performing the classic gesture of smelling a cannabis flower or bud in an attempt to identify the variety, what we are basically doing is smelling terpenes. In fact, it is the terpenes that give each variety of cannabis a unique taste and smell that make it different from the other varieties. But is that all that terpenes give? A gourmet touch to each variety?
After saying that they are part of popular medicine, it is easy to guess the answer. Terpenes are much more than smell and taste; they are very interesting compounds in their own right, with the ability to cause many effects. Despite the simplicity of their chemical composition, little more than carbon and hydrogen, they are compounds that make themselves felt even at very low concentrations. It is considered that they hold pharmacological interest at concentrations above 0.05%[1], which is way below the 0.2% of THC. But their true secret lies in their ability to combine effects. Their individual effects have been known for a long time. Today, it is beginning to be understood that their real potential lies in their ability to add effects and generate synergies.
[1] E. B. Russo (2011).
In cannabis, terpenes interact with each other to produce a great diversity of alliances and synergies. But they also interact with cannabinoids, modulating and shaping their effects. This interaction between terpenes and cannabinoids seems to be the cause of the diverse effects of different types of cannabis. Depending on the terpenes that accompany cannabinoids, it seems that their effects can be more or less intoxicating, more or less stimulating, more or less anxiolytic, more or less analgesic, or more or less anti-inflammatory.
People talk about getting “high”, but cannabis is much more than an intoxicating effect. There are psychedelic effects, euphoric effects, energising effects, creative effects… effects that make you want to laugh, enhance your empathy or make you more talkative. But cannabis can also create anxiety and paranoia, increase appetite or the feeling of insatiable hunger, and produce lethargy and somnolence, as well as a racing heart beat or difficulty in sleeping. So it’s starting to become quite complicated, such an enormous number of effects, many of them the opposite of each other, produced by the same plant.
And, in any case, where does this diversity of cannabis effects come from? Among all of the plant’s psychoactive compounds, it seems that terpenes play a crucial role in this diversity. More than 400 terpenes have been identified as being present in the different varieties of cannabis to a greater or lesser degree. Each one contributes its particular aroma and flavour, but also certain characteristic effects. Some of them are sedative, others are stimulant. Some of them are anxiolytic, others are anxiogenic. There are analgesic effects and also anti-inflammatory effects. Intoxicating, stimulant, digestive, antispasmodic, short-term memory enhancing… the list gets longer and longer, as does the diversity of effects of cannabis.
Using the classic distinction between “sativa” (Cannabis sativa) or stimulant plants, and “indica” (Cannabis indica) or sedative plants, we could propose classifying terpenes in cannabis on the basis of their sedative or stimulant effects. So, we could perhaps say that there are specifically indica terpenes and specifically sativa terpenes. However, it turns out that it’s not as simple as that. Terpenes can be blended in a practically infinite number of ways. For example, myrcene, with a strong sedative potential, is the most common terpene in cannabis, and is not specific to the varieties with an indica profile. Limonene, known since pre-cannabis times for its stimulant properties, should be a sativa terpene. And in fact it is. A strong presence of limonene or, to put it another way, a strong, sweet citrus smell and taste with a touch of lemon is symptomatic of the stimulant and energising varieties, which have been traditionally known as sativa types. But what happens when we find the unmistakeable aroma of limonene blended with a strong presence of myrcene? Here is where terpenes’ magic starts. Suddenly we see that this meeting of intentions and effects of each terpene generates synergies that are more subtle than the mere sum of their parts. We find that this union of terpenes, even when it is accompanied by high levels of THC with almost no presence of CBD, has anxiolytic effects that are even able to modulate the “high” produced by these high levels of THC and produce a state of calm and mental well-being.
Does this mean that when we find that myrcene and limonene are present in higher quantities than the other terpenes, we will have cannabis with an anxiolytic profile? It seems that it’s more complicated than that. Synergies between terpenes are so complex that subtle hints of any terpene not only modify its taste and smell, but are also capable of modifying its effects. So we can’t rush to conclusions. But how can we get our bearings if the same variety can have more than 100 terpenes? Perhaps the best approach would be to focus on those that are present in the highest concentrations in cannabis. There are terpenes that are found more frequently in the different varieties and, as a general rule, they are usually found in higher concentrations. These predominant terpenes play a significant role in cannabis. We’ll briefly talk about six of the terpenes found most commonly in the plant.
Myrcene
This is the most widely found terpene in cannabis. It has a sweet, fruity smell. Exotic but with an earthy touch. It is a powerful sedative and relaxant. It is also found in mangos, hops and guava. It enhances the effects of THC and is possibly the terpene mostly responsible for the sedative effect of cannabis.
Beta-caryophyllene
Its smell is reminiscent of pepper, with woody and spicy hints. Obviously, it is found in pepper and it is also present in almost all the varieties of cannabis. It also has a relaxant and sedative profile.
Limonene
Considered the quintessentially sativa terpene, it is not exclusively sativa. With a smell and taste of sweet citrus with lemony notes, it is found in most citrus fruits. It has stimulant and anxiolytic effects.
Pinene
Possibly the most widespread terpene in the plant kingdom, it is commonly found in cannabis as well. It is present in pine trees and conifers; it has a fresh, spicy smell that makes you think of pine woods. Its effect is mainly energising, but it is also calming, and is able to “relax” the effects of THC.
Linalool
A flowery scent, especially of lavender. It has been known for thousands of years for its powerful sedative and sleep-inducing effects. It is naturally found in jasmine, thyme, and especially in lavender.
Humulene
A very versatile terpene, smelling of fresh hops and freshly cut grass. It has a certain bitterness reminiscent of hops, and also an earthy note. It is a stimulant and it is found in hops, black pepper, ginseng and sage.
Although terpenes can be identified and their individual effects are known, what makes them so interesting is how they combine. And finding our way through terpenes is no easy matter. We have answered pretty much all the questions with more questions. We have one fact to start with: terpenes’ ability to produce pharmacological effects. Knowing this, it is not hard to see how they combine with the effects of cannabis. However, when trying to predict the effects of cannabis from its terpene composition, we come up against the problem of recognising them and understanding their synergies and interactions. But despite this complex labyrinth, there is something in our complicated relationship with terpenes that may be able to explain the diversity of effects of cannabis. It is becoming increasingly clear that terpenes play a fundamental role in the effects of cannabis, and that they have an enormous capacity and ability for modulating cannabinoids, including the one that everybody knows, tetrahydrocannabinol, more popularly known as THC. This is the cannabinoid that has received most attention, and has been selected with so much care by so many growers that it has become the main psychoactive compound in the cannabis plant, and the main culprit in all the policies that seek to regulate the use of cannabis. And now we find that simple hydrogen and carbon chains called terpenes are able to modulate it.
This opens an enormous field and it seems that there is nothing for it but to develop our sense of smell if we want to predict and/or understand the effects of each variety of cannabis. Perhaps it is also very important to analyse terpenes in cannabis at the laboratory. If cannabis users could compare aromas and flavours with laboratory results, they could start to associate their experiences with certain terpenes and, in turn, this would enable them to predict certain qualities of each variety. It’s not just a matter of knowing how much THC there is and how much CBD counteracts it. Terpenes play a fundamental role in the effects of THC and of cannabis in general. By identifying them, we can predict effects and this gives us an invaluable risk reduction (RR) strategy. By putting names to the infinite variety of smells, tastes and effects of cannabis, perhaps we can minimise risks by adapting the plant to people and its uses; otherwise, it is people who end up having to adapt to the plant and its “fads”.
Bibliography
Russo E. B. Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects, Br J Pharmacol. 2011 Aug:163(7):1344-64.
Russo E. B. The Case for the Entourage Effect and Conventional Breeding of Clinical Cannabis: No “Strain,” No Gain. Front. Plant SCI. 2019 Jan 9;9:1969.
Mudge E. M., Brown P. N., Murch S. J. The Terroir of Cannabis: Terpene Metabolomics as a Tool to Understand Cannabis sativa Selections. Planta Med. 2019 Jul;85(9-10):781-796.
Smith C. J., Vergara D., Keegan B., Jikomes N. The phytochemical diversity of commercial Cannabis in the United States. PLoS One. 2022 May 19;17(5):e0267498.
[1] E. B. Russo (2011).
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