Terpenes: Why Does Marijuana Smell?

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man smelling the terpenes on ripe cannabis buds with delighted and intrigued expression

Cannabis Derived Terpenes



Cannabis comes with a wide variety of aromas. Some are sweet and pleasing, others are musky and off-putting. Regardless of how it hits your nose, you are experiencing the plethora of terps that marijuana buds possess. Loud, dank, gassy, fruity, floral, spicy, earthy, peppery, these are all words used to describe the scent of various cannabis strains. These odors are terpenes, but what is a terpene?

What are Terpenes?

Terpenes are considered Volatile Organic Compounds (VOCs) but don’t let the word volatile scare you, it simply refers to how these molecules evaporate into the air at low temperatures. Terpenes begin to volatilize in the 30-31 celsius range, although this is much lower than both their flash point and their boiling point.

Technically speaking, terpenes are hydrocarbons with small isoprene units linked to one another to form chains. A related term that you will also see in text, is terpenoids. Terpenoids are terpenes which contain an extra oxygen molecule.

Terpenes in weed are why the Cookies strain smells (and tastes) different than the Skittlez strain or OG Kush or Blue Dream or Durban Poison. Other constituents, like thiols and esters, contribute to the overall aroma profile, but they are less understood compared to the aromatic impact of terpenes.

The main types of terpenes and terpenoids found in cannabis are monoterpenes, sesquiterpenes, diterpenes and triterpenes (1). In a paper published at the end of 2020, more than 200 volatiles have been reported from different cannabis strains, of which 58 monoterpenes and 38 sesquiterpenes have been characterized (2). It is the varying combinations of these terpenes that create the unique aromas wafting from cannabis buds.

Terpenes are a secondary metabolite of the cannabis plant. Another set of secondary metabolites in cannabis are cannabinoids. There are many types of cannabinoids in marijuana strains, but the most frequently studied cannabinoids are THC, CBD, CBG, THCV, and CBN. Cannabinoids are concentrated in the resin heads of the stalked trichomes, so too are the terpenes. Unlike terpenes, the cannabinoids do not add to the aroma of marijuana strains.

Gardening practices, growing environments, the type of soil, harvesting, curing, and even storage conditions can all affect the smell of cannabis flower and concentrates. Terpenes are not exclusive to Cannabis sativa, indica, and ruderalis and all their hybrid strains. Terpenes exist all around us in nature. They are a primary constituent of the essential oils created by plants. The wide array of terpenes give everyday objects the familiar smells we all associate with them.

 

terpene effects chart with examples

Many of us feel refreshed by the citrus smell of a freshly peeled orange. You can thank the monoterpene limonene for that aroma. Reactions from essential oils used in the aromatherapy field are well studied. Aroma therapists use the same terpenes that we find in the cannabis plant, although they are extracted from different sources.

Picture yourself walking through a pine tree forest on a warm summer day, you can smell the pine in the air as you wander through the woods. This smell is created by a monoterpene named alpha-pinene. Lavender is another scent most people are familiar with. Guess what… that smell is largely from the monoterpene linalool.  As you can quickly see, terpenes are all around us, in nature, cannabis, and hemp too.

In nature the development of terpenes serves two primary functions. The first is as a natural pest deterrent. Certain plants will let off a smell (terpenes and terpenoids) to deter pests from eating them. At the same time, plants also use terpenes to attract pollinators. The sweet smells attract pollinator insects so that the plant has an increased chance of reproduction. In nature, terpenes are used as mechanisms to help ensure the survival of the species.

Do Terpenes Enhance Cannabinoids?

Terpenes and terpenoids display unique therapeutic effects that may contribute meaningfully to the entourage effects of cannabis based medicinal extracts (3). When these terpenes are ingested through cannabis flower or cannabis edibles, they combine with the cannabinoids in a synergistic way to create what is known as the Entourage Effect. Some experts have referred to terpenes as the “steering wheel for your experience”.  THCa isolate (THC content is the main cannabinoid responsible for psychoactive effects) and other cannabinoids in the absence of terpenes have a profoundly different experience on those who consume it compared to the full spectrum effects of dried flowers. It is not uncommon for extracted terpenes to be added back into concentrated products or edible products in order to offer different flavor and experience profiles to the end consumer in addition to the advertised THC levels.

The exploration of cannabis-related terpenes and their role in the body is ongoing. One of the first papers to tackle the question was published in 2011 by Dr. Ethan Russo, entitled Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects (4). Dr. Russo has emerged as a leading scientist in the field. His work has been the basis for many of the breakthroughs in our understanding of terpenes, cannabis, and our body.

Are Cannabis Terpenes Bad for You?

At the end of the day cannabis terpenes are no different than terpenes derived from other sources, like lemons, pine needles, or lavender. Water can be toxic, if consumed in excess amounts, so can terpenes. Terpene content in cannabis do not reach a level of concern in regards to harmful amounts whether it is inhaled, ingested, or applied topically.

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What are the Different Cannabis Derived Terpenes?

Researchers have identified at least 120 terpenes produced within the cannabis plant(5).The majority present themselves in barely detectable amounts. Cannabis flowers generally consist of 2-3% or lower total terpenes by weight. Comparatively, the cannabinoid THC, tends to test in the 20%+ range for dried flowers on a regular basis.

Many of us have a favorite smell or profile to the cannabis we enjoy most. Common monoterpenes in cannabis include limonene, b-myrcene, β-pinene, linalool, a-terpinolene, and trans-ocimene. Predominant sesquiterpenes include β-caryophyllene, α-humulene, nerolidol, and b-farnesene, amongst others. Next time you stop by the dispensary, check to see if your label contains this information.

Five Frequently Found Cannabis Terpenes

Limonene

Limonene terpene citrus plant collage with skeletal formula chemical structure

Cannabis connoisseurs in search of a light, fresh, citrus sensation often gravitates towards limonene dominant strains. Limonene terpenes are one of the easiest to identify terpenes in cannabis. The citrus scent of limonene opens your eyes as it enters your airways, it excites your mind and prepares you for the day ahead.

Limonene is a monoterpene whether it is found in nature or in the cannabis plant. Common sources of limonene terpenes include the rinds of grapefruits, oranges, limes, lemons, and mandarins. Several trees emit limonene as well. Cottonwoods, red and silver maple trees, as well as oak trees all have detectable traces of this terpene. Formally, limonene is referred to as d-limonene, its main chemical form.

Commercial uses for limonene terpenes are all around us as well. Limonene is a common flavoring agent in food, beverages, and chewing gum.  Fragrance products, lotions, suntan products, and cosmetics like eye shadow, lipstick, and mascara all contain limonene as part of the essential oils. Limonene is found in many of your household cleaners. Hand soap, industrial cleaners, degreasers, and strippers commonly contain limonene as a solvent to clean surfaces.

In high concentrations this terpene has been known to be a potential skin irritant. No worries with your CBD oil though, the limonene content in the cannabis plant does not reach a level of concern. Limonene has also been rated and approved as a pesticide. Limonene can be used as flea and tick control on pets, a mosquito larvicide, and an effective measure to control white flies, mealy bugs, scale insects, and many other waxy coated bugs.

With all of these known uses, there has been a considerable amount of research put into the safety and medical efficacy of limonene terpenes. A fascinating attribute is that limonene is an effective sorption promoter, which is an accelerant for improved transdermal drug delivery and works by penetrating the skin to reversibly decrease barrier resistance (6). This fact comes in particularly handy when discussing the effectiveness of topicals containing CBD, THC, or any of the other cannabinoids.

Limonene has been recognized as an effective antioxidant, which is important to protecting overall cell health. In a study, d-limonene has been shown to have anti-proliferative and apoptosis-inducing effects (on certain cancers), thus it has been used as a chemopreventative and chemotherapeutic agent against multiple types of tumors (7). Limonene has also been studied as a promising method to lowering triglycerides and promoting the increase of “good” cholesterol, both of which are key to overall heart health.

Myrcene

myrcene terpene plant collage with skeletal formula chemical structure

One of the most prevalent terpenes in cannabis is the monoterpene myrcene. Myrcene is the terpene you commonly hear being associated with the sedative experience of some marijuana strains. Between α-myrcene and β-myrcene, the latter is more common to find in cannabis and nature. Myrcene has an organic air to it, essences of earthy aromas and musk lead the way. Those smells are complemented by muted notes of sweetness and occasional spice.

Myrcene terpenes appear in many herbs. Basil, parsley, verbena, and lemongrass are a few examples. Myrcene is also found in fruits, mangoes and guavas being amongst those with the highest concentrations. You might be thinking, but those all smell different from each other. This illustrates for you how it is the unique combination of common terpenes that make each herb, fruit, and medical marijuana strain smell different.

Myrcene can be found outside of the cannabis plant in a variety of other species, including Hops. You might be aware that hops are used in the production of beer,  but did you know that hops also happens to be a close relative to cannabis? They are both in the Cannabaceae Family of plant taxonomy. Hops are probably the best known cousin of cannabis.

This terpene can be found in products all over the house. Myrcene is a common food and beverage additive being used primarily as a flavoring agent. Dishwashing soap, floor cleaners, laundry detergent, and air fresheners are a few of the industrial applications that incorporate myrcene as an ingredient. Although they are strong enough to serve a purpose in the industrial examples above, Myrcene terpenes are also sensitive enough to be used in cosmetics and antiperspirant deodorants.

Being as such, myrcene has undergone a significant amount of human trial research in an effort to determine benefits, potential harms, and modes of action within the body. Because myrcene is not unique to cannabis, yet still the same as myrcene found in cannabis, we can draw some conclusions from previous research to its efficacy on specific human conditions.

Most notable of those findings, is the sedative effect of myrcene, known in the cannabis culture as “couch-lock”. Cannabis strains which contain high concentrations of myrcene (>0.5% myrcene) are likely to induce sedative qualities (8). Other studies have investigated the potential of myrcene to impart analgesic, antioxidant, anti-inflammatory, antibacterial and anticancer effects (9).

Pinene

pinene terpene plant collage with skeletal formula chemical structure

Pinene is the most common monoterpene found in nature. Pinene has an alpha and beta version, referred to as alpha-pinene and beta-pinene. Each form presents a slightly different aromatic profile. Most people can recognize the scent of α-pinene, because it is the same scent exuded from pine needles in the forest. Less common is β-pinene, which has a woody, earthy scent.

Many popular herbs, such as rosemary, sage, and mint contain α-pinene, as do conifer trees (pine, spruce, fir ect.). The less common β-pinene appears in the essential oils of parsley, dill, and basil.

Many household and industrial cleaning products have a pine scent to them. Alpha-pinene is an important component of turpentine, a popular chemical used in cleaning products. Another product sector in which pinene is widely used, is in the production of insecticides. Small doses of pinene are considered pleasant, and this is why we find α-pinene as a popular scent in candles, air fresheners, and perfumes.

Like many of the other terpenes found in cannabis, pinene is used in commercial applications, therefore, it has been the subject of numerous safety studies. A characteristic that makes both α-pinene and β-pinene standout as a terpene for medicinal applications, is this terpenes partial water solubility. This unique attribute gives pinene the ability to cross the blood-brain barrier and interact directly with the central nervous system (CNS).

Various studies investigating pinene have shown positive health benefits including antibiotic resistance modulation, anticoagulant, anti tumor, antimicrobial, antimalarial, antioxidant, anti-inflammatory, and analgesic effects. Some of the more prominent effect of a-pinene and b-pinene include cytogenetics (cell and chromosome creation), gastroprotective, anxiolytic (anxiety reduction), cytoprotection, anticonvulsant, and neuroprotective effects (10).

Although cannabis possesses both forms of pinene as it is found elsewhere in nature, the terpenes used in these studies were not cannabis derived. Another attribute of note, specifically of α-pinene, is that it can act as a bronchodilator. A-pinene has been used to treat respiratory tract infections for centuries (11).

Linalool

Linalool terpene plant collage with skeletal formula chemical structure

Linalool is a monoterpene found in cannabis that imparts a sweet, floral, and sometimes woody scent, with a hint of citrus. The scent of linalool has been described as possessing calming and soothing properties. If you’ve ever had the chance to walk through a field of lavender on a warm summer day, the beautiful and relaxing scent in the air is linalool.

Linalool is a major terpene in the essential oil of lavender. Linalool can be found in many places outside of cannabis, plants such as coriander, sweet basil, bergamot mint, thyme, and clary sage all contain high levels of linalool terpenes.

Laundry detergents, fabric softener sheets, carpet cleaners, disinfectant sprays, multi-purpose cleaners, and dishwashing liquid are just a few of the likely products in your home with linalool terpenes.  In the bathroom you may find linalool in your shampoo, skin cream, moisturizers, hair dyes, as well as in your antiperspirant and deodorant.

Linalool has been demonstrated to not only activate olfactory receptors but also to modulate other various receptors internally, including receptor responses in the central nervous system. The CNS (central nervous system) through extensive study, has been shown to be strongly involved in sedative, anxiolytic (anti anxiety), and the calming processes (12).

In addition to the sedative and anxiolytic properties of linalool, this terpene has demonstrated abilities as a local anesthetic, an anticonvulsant, analgesic (pain relief), anti-inflammatory, anti-tumoral, anti-microbial, antioxidant, and cholesterol lowering agent (13).

Linalool has been categorized as an absorption promoter in topical preparations by increasing the skin permeability, which allows for better penetration of other therapeutic agents (like CBD oil). Interestingly, animal studies have shown that internally, linalool is rapidly absorbed by the intestinal tract and travels into the bloodstream after oral ingestion.

Caryophyllene

caryophyllene terpene plant collage with skeletal formula chemical structure

Caryophyllene at one point was classified as α-caryophyllene and β-caryophyllene, but α-caryophyllene has been renamed to α-humulene. The aroma of β-caryophyllene is a classic one that many old school smokers will know well. The smell is the peppery, spicy, hash-like aroma of a β-caryophyllene dominant marijuana strains. The aroma of α-humulene consists of earthy notes.

Caryophyllene is a sesquiterpene whether it is found in nature or in the cannabis plant. A natural source that β-caryophyllene is found in abundance is black pepper. You will also find caryophyllene in clove, oregano, hops, cinnamon, and basil.

Caryophyllene (as well as the other terpenes mentioned in this article) is a common component  in the food industry as a food additive and flavoring agent that has GRAS (Generally Recognized as Safe) status and is approved by the FDA and EFSA for food uses (14). The aromatherapy industry heavily relies on caryophyllene terpenes to use in lavender scented candles, incense, and essential oils for diffusers.

Whether caryophyllene terpenes are derived from cannabis or not, they hold a unique distinction amongst terpenes as being one that can directly bind with the cannabinoid receptors in our Endocannabinoid System (ECS). CB receptors are located through-out our body and brain. Cannabis has many common cannabinoids, with the most famous being delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), which bind and interact with our CB1 and CB2 receptors.

Although the CB1 receptor is responsible for the psychomodulatory effects, activation of the CB2 receptor is a potential therapeutic strategy for the treatment of inflammation, pain, atherosclerosis, and osteoporosis. It has been reported and verified that the widespread plant volatile b-caryophyllene selectively binds to the CB2 receptor and that it is functioning as a CB2 agonist, leading to cellular activation and anti-inflammatory effects (15).

Many studies have demonstrated its antioxidant, anti-hyperglycemic, organoprotective, and anti-inflammatory properties. B-caryophyllene appears as a promising molecule for diabetes and its complications (16).

Indica vs Sativa Terpenes

Myrcene terpenes, as noted above, provide a sedative experience if they are in the right concentration. Between Cannabis indica and Cannabis sativa strains, indica-dominant strains are more frequently associated with sedative effects. Most people report effects of sativa-dominant strains as having energetic and euphoric effects, so does that mean myrcene terpenes are only found in indica strains?

Sativa strains are often associated with terpenes that are citrusy, fruity, and sweet. Does that mean limonene terpenes are exclusive to sativa strains? Do sativa plants have more terpenes? The question of whether certain terpenes are exclusive to either indica or sativa strains has been investigated, most recently in a paper published in May 2022 titled – The phytochemical diversity of commercial cannabis in the United States (17).

This study revealed distinct clusters of commonly co-occuring terpenes. If the prevailing labeling system of indica, sativa, and hybrid were accurate, we would expect to see a reliable difference between the terpene profile of samples associated with the labels. The results of the study provided visualization through charts that there is a large overlap of terpenes in indica, sativa, and hybrid cannabis strains.This is most likely due to cross-breeding which has hybridized every weed strain and maybe its time to reorganize how we view different cannabis plants.

Because cannabis strains can’t be cleanly divided by the indica or sativa classifications, in many scientific communities, researchers are referring to cannabis plants as unique “chemovars”. This term represents the chemical (cannabinoids, terpenes, ect.) make-up of each strain and serves as a replacement for the out-dated terminology of indica vs sativa, in the scientific context.

chemovar example showing cannabinoids and terpenes

The results of the study indicate that even a simplistic labeling system, in which THC-dominant samples are labeled by their dominant terpene, is better at discriminating samples than the industry-standard labeling system. To answer the question of – are terpenes specific to either indica or sativa strains, the answer is no. There is no known exclusivity for terpenes between them.

Terpenes, Weed at Home in the Garden

If you’ve ever had a plant that seemed to change its smell during different stages of growth, you’re not making it up. It’s not uncommon for the terpene profile to change at different times of the plants life, all the way up until it is cured.

The stalked trichome with the ball on top (aka capitate stalked trichome) is the one we all see in pictures. These tend to be heavily concentrated on the buds and contain the largest proportion of monoterpenes. Sesquiterpenes are found in higher concentrations on the capitate sessile trichomes, which appear most frequently on the sugar leaves.

close up of stalked trichomes on cannabis buds and sugar leaves

Terps in the Modern Cannabis Industry

With legalization, cannabis consumption behaviors and products have changed, not everyone wants to smoke cannabis flower. Topical applications (like CBD oil) aren’t meant to be ingested, but topicals harness the power of terpenes as well. Vape cartridges are another place we see a modified use of terpenes. In the cannabis extract distillation process, cannabinoids and terpenes are separated and then recombined to create custom formulas.

Terpenes can be found in many places aside from cannabis. Companies are extracting non-cannabis derived terpenes and adding them to cannabis products, which has drawn some pushback from consumers and lawmakers. Dr Ethan Russo has partnered with True Terpenes, which manufactures specific terpene blends and sells them for use in topicals, distillates, tinctures, and edibles.

As the industry and the knowledge advances, consumers can expect more of the custom terpene blends to be introduced. In some commercial markets, manufacturers treat their flowers with different types of terpenes post-harvest. This increases the pungency of the flowers, and these strong aromas are a perceived value by the consumer. In many cases, this practice is not relayed to the end user who may experience a rougher smoke. (Another reason why it’s better to grow your own weed at home!)

 

Cannabis Terpenes Fun Fact

Drug dogs were not trained to smell cannabis in the past, they were trained to detect terpenes. Specifically the sesquiterpenes: b-caryophyllene, a-caryophyllene (also known as a-humulene) and the monoterpene, pinene. With the legalization of cannabis in many areas of the world, a good number of K-9 units are being retrained or more commonly, retired.

drug dog smelling terpene rich cannabis plant

Impact and Future of Terpenes

Terpenes are an impactful component of cannabis use. We are still learning more about the effects terpenes have and we are continuing to discover new terpenes within cannabis each year. Testing for terpenes is now part of many legal markets and thus, there has been an improvement in the calculations and testing processes by cannabis testing labs.

Consumers are always looking for new and exotic aroma profiles, and this has led to breeders focusing on the diversity and quantity of terpenes in marijuana strains that they grow. Legalization has opened the doors for breeders to germinate thousands of seeds at a time, looking for those special few terpene profiles that will make the cut.

Universities and researchers are now able to conduct cannabis specific studies. The knowledge we gain surrounding terpenes, cannabinoids, and their synergistic properties is expanding on a constant basis. We know through existing studies that terpenes have a whole range of benefits and the range of uses in other industries confirm their potentials.

Next time you are at the cannabis shop, ask your bud tender about the terpene profiles. Try a few strains that are dominant in an individual terpene, and journal how they made you feel. If you are able to find a terpene or ratio of terpenes that works best for your desired results, wouldn’t it be easier to shop using terpene profile instead of indica or sativa?

Limonene Dominant Strains

  • Jack Herer
  • OG Kush
  • Super Lemon Haze
  • Sour Diesel

Myrcene Dominant Strains

  • Grand Daddy Purple
  • Animal Mintz
  • Northern Lights
  • Strawberry Cough

Pinene Dominant Strains

  • Blue Dream
  • Dutch Treat
  • Blueberry Gelato
  • Galactic Glue

Linalool Marijuana Strains

(Many strains feature linalool, but few are dominant in this terpene)

  • Amnesia Haze
  • Lavender
  • Do-Si-Do
  • Skittlez

Caryophyllene Dominant Strains

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Terpene FAQs

Is it good to smoke terpenes?

With some of the benefits mentioned above, many people will naturally wonder, what does smoking terpenes do? It all depends upon the amounts and concentrations. Terpenes can be smoked in an isolated form, or as part of something, like cannabis flower. In an isolated form and in a high enough dose, these terpenes can be toxic. So, are cannabis terpenes bad for you? No, in the levels consumed by ingesting cannabis, the terpene concentrations that are naturally found in weed do not pose health risks.

What effects do terpenes have?

Terpenes can have a variety of effects including better delivery of cannabinoids to the body by being a sorption promoter. Having this effect accelerates transdermal drug delivery in topical applications. Other terpenes have the ability to cross the blood-brain barrier and interact directly with our CNS. Terpenes also hold powerful olfactory effects. Smells have the ability to change moods, the effects from exposure to specific terpenes is the foundational knowledge behind the aromatherapy industry.

What terpenes help with high?

When consuming cannabis, it would be extremely rare to find a strain with only one terpene. Cannabis has a variety of terpenes in different levels that combine with cannabinoids to create unique experiences. We covered the terpenes that are found in the largest proportions, and despite many cannabis strains having those same terpenes, it’s the ratio of those terpenes that make each strain unique. Yes, terpenes will increase your high. Synthetic THC and THC isolate in the absence of terpenes is a very different high compared to full spectrum flower.

What does terps mean in weed?

“Terps” is the shortened nickname for terpenes.  Terps in weed are the volatile chemicals that are responsible for the smell and taste of your cannabis flower. Terps also contribute the high experienced when marijuana is consumed.

References:

1 ** https://www.karger.com/Article/FullText/509733

2 ** https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7763918/

3 ** https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3165946/

4 ** https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3165946/

5 ** https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181184/

6 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2751457/

7 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6152265/

8 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8326332/

9 – https://www.frontiersin.org/articles/10.3389/fnut.2021.699666/full

10 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920849/

11 – https://pubmed.ncbi.nlm.nih.gov/34365295/

**** blood brain barrier explanation – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697631/

12 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4594031/

13 – https://www.umfiasi.ro/ro/academic/programe-de-studii/doctorat/Documents/Abilitare/2019/Domeniul%20Farmacie/Conf.%20univ.%20dr.%20APROTOSOAIE%20Ana-Clara/9.pdf

14 – https://www.sciencedirect.com/topics/medicine-and-dentistry/caryophyllene

15 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2449371/

16 – https://pubmed.ncbi.nlm.nih.gov/32998300/

17 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9119530/

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