What are Terpenes?
Get to know these aromatic cannabis compounds and what they can do for you.
More and more people are interested in cannabis molecules called terpenes, which not only give cannabis its signature scent but may even have health benefits. Here’s a closer look at what terpenes do, and how they may aid in symptom management:
What are terpenes?
If you feel like “terpene” sounds a lot like “turpentine,” you’re on the right track. In the mid-1800s, scientists studied strong-smelling turpentine to try and find the source of its aromatic properties. Eventually, they discovered its odour-making molecules and named them “terpenes,” a word we continue to use today as the collective noun to describe over 15,000 different fragrant compounds found in nature, including cannabis.
Resembling broken honeycombs with pentagon-like molecules, all terpenes are made up of varying combinations of five carbon molecules and eight hydrogen molecules, called isoprenes. This is why you may come across words like monoterpene (C₁₀H₁₆), sesquiterpene (C15H24), and diterpene (C20H32). Some terpenes may even have the same number of molecules but different structural configurations, known as isomers for the science-minded. For example, alpha-Pinene and beta-Pinene are made up of the same molecules and even smell similar to each other, but not quite the same, because of how they’re built.
Plants, insects, and even some animals produce terpenes that function like aromatic radio signals to communicate with the world around them. In plants, terpenes can help repel predators, attract pollinators, and even send a message to the enemy of their enemy. When spider mites attack the lima bean plant, it releases a specific terpene to attract an insect that preys on the offending mites.
Cannabis terpenes are mostly found within microscopic frosty hairs covering the flower buds and surrounding leaves, called trichomes. Resembling little mushrooms under a microscope, trichomes manufacture a heady cocktail of cannabinoids and terpenes. The larger and more numerous the trichomes, the more abundant the terpenes in a given cannabis plant. However, depending on how cannabis is harvested and manufactured, the resulting product may retain many of the plant’s terpenes or none at all.
Cannabis produces hundreds of terpenes in almost endless combinations, which is why each cannabis strain has its own unique smell, from sweet candy to stinky cheese. While many people assume cannabinoids THC or CBD are responsible for a strain’s scent, these compounds are in fact odourless—the taste and smell of cannabis are evidence of terpenes at work. And while THC and CBD can be influenced by environmental factors such as humidity and sunlight, terpenes are primarily inherited, and unchanged by external factors. This makes terpene composition a more reliable indicator of a plant’s origin than cannabinoid percentage, strain name or Indica/Sativa/hybrid classification. But because Health Canada does not require cannabis companies to list terpenes on the label, at this point, it’s rare to see a breakdown of these compounds on cannabis products.
How do terpenes work in the body?
No longer simply regarded as a pleasant by-product of cannabis, terpenes are emerging as heavyweights in a patient’s search for symptom management. While scientists are just starting to understand the role terpenes play in conjunction with other cannabis compounds, often referred to as the entourage effect, they do help explain why a patient’s subjective experience can change from one strain to another. For example, imagine sampling chicken soup from every home in your neighbourhood: same basic soup, but different ingredients, and a unique taste experience from one house to the next.
We know THC and CBD stimulate cannabinoid receptors found throughout the body through a lock-and-key mechanism. However, the role terpenes play in the overall effect cannabis has on the body is not so easily understood. Some studies have demonstrated terpenes as having little to no effect on cannabinoid receptors, except for beta-Caryophyllene. However, other studies have shown that terpenes stimulate different receptors within the body, which may have a cascading effect on how the body responds to THC and CBD. In other words, terpenes appear to have an indirect influence on our cannabinoid receptors, although the research is still young. Terpenes may also mimic the effects of THC or CBD through other bodily systems. For example, the terpene beta-Myrcene has a known sedative effect, and its presence in cannabis can make the product feel more potent in THC than it is.
Is there a difference between inhaling terpenes and ingesting terpenes?
There are multiple studies on the observed effects of inhaled terpenes, from anxiety and depression to pain management and even memory recall. While these studies were conducted with terpenes from non-cannabis sources, experts know how inhaled terpenes behave in the bloodstream. What we don’t yet know for sure is how the human body metabolizes terpenes when ingested. For example, when the stomach and liver metabolize the cannabinoid THC, it changes from delta-9 to delta-11 THC, which is more effective at crossing the blood-brain barrier. Early studies and animal trials on ingested terpenes are emerging, but definitive science on human implications is yet to be determined.
Think of the difference between fresh rosemary and the dried variety in your spice rack: one has a multidimensional aroma, while the other is more subtle and flat. Cannabis terpenes in dried flower form are no different: loss begins at harvest when cannabis flower is trimmed and dried. One study found that while monoterpenes quickly degraded after harvest, sesquiterpenes, diterpenes and triterpenes remained mostly intact, and some even increased. This isn’t to say monoterpenes disappeared altogether, but they were the most sensitive to the drying process and degraded more quickly. However, like any dried herb, the terpenes in cannabis flower will slowly degrade over time.
What are exogenous terpenes?
There are terpene-only products on the market that are not regulated under the Cannabis Act as they are not made from cannabis. Called “exogenous” terpenes because they’re made from external sources such as hops (a close botanical cousin to cannabis), they’re often marketed as complementary products to cannabis for a more robust, full-spectrum experience. However, patients should be cautious that exogenous terpenes are not as heavily monitored and regulated as cannabis products. If you have questions about adding exogenous terpenes to your treatment plan, reach out to our Shoppers Cannabis Care team via our online form, or reach out to your healthcare professional.
Are essential oils the same as terpenes?
While terpenes make up most of the compounds found within essential oils, they are not the only molecules present. In its most basic form, an essential oil is the liquid concentration of a particular plant; its “essence”, according to the ancient Greeks who coined the term. A cold-pressed lavender essential oil, for example, will contain a mix of terpenes and other phytochemicals that reside in the lavender plant itself. But a product of pure Linalool—the floral terpene responsible for most of lavender’s scent—would not only smell different than lavender essential oil because it lacks the other components, it would be considered an exogenous terpene.
While cannabis was largely prohibited from study until recently, researchers have been able to analyze individual terpenes for nearly two centuries. Below is a list of observed effects in some of the terpenes found in cannabis; however, keep in mind that all the components of cannabis work synergistically together.
Myrcene: The most abundant terpene found in cannabis and many varieties of hops used in beer, both Myrcene and beta-Myrcene have demonstrated sedative effects when paired with THC and CBD. Also found in mangos, tea tree, celery, lemongrass and cardamom, herbal and earthy myrcene may also help with:
Limonene: Readily found throughout the plant kingdom, Limonene is common in cannabis as well as all citrus fruits, juniper and dill. Anecdotal evidence suggests Limonene-rich cannabis improves one’s mood, plus the terpene may also help with:
Pain management and sensitivity to pain
Berry White, Durban Poison and AQ-Balance-OLC God Bud X by Aqualitas are cannabis strains/cultivars known to be high in Limonene.
Alpha-Pinene: The most common terpene in nature, woodsy alpha-pinene is far more abundant in cannabis than its isomer, beta-pinene. The very first terpene discovered inside fragrant turpentine, there is some evidence alpha-pinene helps with memory, and anecdotal observations suggest cannabis with alpha-pinene produces fewer unwanted side effects, such as memory loss. It may also help with:
LA Confidential, Bubba Kush and Blue Dream by Pure Sunfarms are cannabis strains/cultivars known to be high in alpha-Pinene.
Beta-Caryophyllene: Also found in black pepper, cloves and cinnamon, spicy beta-Caryophyllene is the only known terpene to bind with a cannabinoid receptor, namely CB2 receptors that are found throughout the body (CB1 receptors are mostly concentrated in the brain). Anecdotal evidence suggests CBD-rich strains high in beta-Caryophyllene may help manage the symptoms of autoimmune disorders such as arthritis. This terpene may also help with:
Girl Scout Cookies, Sour Diesel and Organic Rockstar Tuna by The Green Organic Dutchman are cannabis strains/cultivars known to be high in beta-Caryophyllene.
Linalool: Found abundantly in lavender, Linalool is also commonly found in cannabis in addition to basil and bergamot, the main ingredient in Earl Grey tea. Cannabis with Linalool has anecdotally helped with the symptoms of anxiety, plus the terpene itself may also help with:
Amnesia Haze, Zkittlez and Wappa by Zenabis are strains/cultivars with high levels of Linalool.
Alpha-Humulene: An isomer of beta-Caryophyllene, this terpene is also known as alpha-Caryophyllene but was formally named after the hops plant, Humulus lupulus, where it’s found in abundance. This earthy, skunky, hoppy scent is also present in evergreen trees, ginger and sage. Humulene is a known antibacterial agent, as it famously kept English beer from spoiling in the 19th century while en route to India, giving rise to hoppy India Pale Ale. Humulene has been observed to have anti-inflammatory effects, and may also be an appetite suppressant.
Nerolidol: While not typically found in high concentrations in cannabis, nerolidol is also present in peels of citrus fruits, corn and tomatoes. This terpene has been found to help with sleep and is well absorbed by the skin, which may prove useful in topical cannabis products.
Geraniol: The abundant terpene in geraniums and roses, geraniol is also the main ingredient in citronella oil used to repel mosquitos. This terpene has been shown to be an effective antimicrobial, which is why it’s commonly used in naturally-derived cleaners. It may also help with inflammation and diabetic neuropathy.
Borneol: A woodsy terpene also found in camphor, mint and rosemary, studies of borneol have demonstrated it may be a drug potentiator, meaning it intensifies the effects of other drugs. It may also help with inflammation and pain management.
Terpinolene: Another terpene that may enhance the sedative effects of THC, terpinolene is commonly found in cannabis as well as pine trees, parsnips, sage and apples. It has also been found to have antioxidant qualities.
Alpha-Bisabolene: This lesser-known terpene is actually quite common in cannabis, albeit in low concentrations. It can also be found in opoponax, also known as sweet myrrh, and is being studied for its potential in cancer treatments.
Delta 3 Carene: A component of turpentine, this terpene is being studied in conjunction with bone growth, yet is also considered a mild irritant.
Guaiol: This woodsy, rose-smelling terpene is also found in cypress trees and guaiacum plants. There are fewer studies on guaiol than other terpene, though it shows promise in the management of symptoms of inflammation.
Ocimene: Grassy and sweet-smelling ocimene is also found in marigolds, parsley and basil, and named after the genus name for basil, Ocimum. Thought to have antimicrobial properties, this terpene is the one that some plants emit when under attack, as with the lima bean and spider mites, to attract another predator.
Farnesene: This lesser-known terpene is also sometimes present in hops, and described as having a woody, floral aroma. Also found in apple peel, farnesene can impart a green apple scent to cannabis. It’s thought to have a calming effect on the body and have some anti-inflammatory properties.