What are terpenes?
Terpenes (pronounced tur-peens) are the organic, aromatic compounds found in plants in the form of oils. They are responsible for a plant’s unique flavour and aroma. In cannabis plants, terpenes are contained in the trichomes of female plants, in the form of sticky resin glands. Cannabis plants contain more than 150 types of terpenes, each contributing to the aromatic diversity of the wide range of cannabis cultivars and strains available.
Until recently, much of the cannabis industry focused almost exclusively on the therapeutic qualities of cannabinoids like THC and CBD. As our knowledge of terpenes continues to grow, it is becoming increasingly apparent that these aromatic compounds are medicinal powerhouses in their own right. Beyond influencing the cannabis plant’s unique taste and smell, terpenes play a significant role in the therapeutic effects of cannabis by interacting with cannabinoids and other cannabis compounds to create clinically meaningful differences in patient experience.
This comes down to synergy — multiple elements of cannabis working together to amplify each individual element’s effect, allowing the overall effect of the plant to be greater than the sum of its individual parts. This phenomenon is known as the ‘entourage effect’.1 When cannabinoids like THC and CBD are paired with terpenes (or certain concentrations of them), they create or emphasise particular medicinal effects — opening up a range of therapeutic combinations that researchers are beginning to explore.
What do terpenes do and what are their effects?
Throughout history, terpenes have been harnessed for a wide range of medicinal purposes. Different terpenes have different effects on the mind and body, with potential capabilities ranging from antibacterial and antifungal to anticancer and pain-relieving.2 The medicinal properties of these aromatic compounds and the way they interact with the endocannabinoid system are still being explored.
Linalool, found in lavender, has been shown to aid sedation and relaxation while reducing aggression and hostility — effects that are clinically relevant when considering terpene profiles for anxious or pain-affected patients.3
Limonene, found in citrus plants, is associated with mood-elevating and antidepressant properties2 — making it worth considering for patients presenting with low mood or affective symptoms.
These are just some of the potential therapeutic effects of terpenes, many of which can be found in cannabis treatments:
- Antiviral: a number of terpenes demonstrate antiviral capabilities, including beta-pinene and limonene4, as well as caryophyllene, camphor, and carvone.5
- Antidepressant: a significant proportion of plant-derived antidepressant compounds contain terpenes, including linalool and beta-pinene.2
- Pain relieving: terpenes including humulene, geraniol, linalool, and β-pinene are capable of activating the body’s CB1 receptors, influencing pain perception. A 2021 study found that combining these terpenes with cannabinoids amplified analgesic effects without an increase in adverse effects — further supporting the entourage effect.6
- Anticancer: terpenes such as limonene7, pinene, camphor, terpinene, and beta-myrcene may help inhibit the activity or growth of cancer cells.8
- Antimicrobial: terpenes including alpha-bisabolol, geraniol, menthol, eucalyptol, and terpinolene may display antimicrobial activity, with potential utility in slowing the progression of harmful microorganisms.9
Much more research is needed — particularly in human populations — to fully characterise the therapeutic potential of terpenes.10 However, preliminary research and a longstanding history of terpene use in traditional medicine indicate that these compounds may offer significant health benefits yet to be fully explored.
Do terpenes make patients high?
Terpenes found in cannabis plants are not intoxicating on their own and will not produce the psychoactive high associated with THC. However, some terpenes are considered psychoactive in the broader sense, in that they can influence brain function — producing effects such as relaxation, mood elevation, or reduced anxiety.
While terpenes alone will not produce intoxication, they may modulate the effects of intoxicating cannabinoids like THC. Some evidence suggests that different combinations of cannabinoids and terpenes may alter — and even mitigate — undesirable THC effects such as anxiety. There is also evidence that terpenes enhance the existing therapeutic properties of cannabinoids, including pain-relieving6 and antidepressant2 effects, when taken together.
How do terpenes differ from cannabinoids (THC & CBD)?
Cannabinoids and terpenes are both organic compounds found in cannabis plants — and both have varying effects on the mind and body — but terpenes are not cannabinoids. Key distinctions include:
Cannabinoids
- A diverse array of molecules found within the cannabis plant, some other plants, and the human body.
- Phytocannabinoids like THC and CBD are largely responsible for the effects patients experience when consuming cannabis, including psychoactive and therapeutic effects.
- Cannabinoids interact with the endocannabinoid system in varying ways to produce effects in the mind and body.
- Heavily regulated in Australia and require a prescription in most cases.
- Cannabinoids like THC are capable of producing an intoxicating effect.
Terpenes
- Also organic compounds found within the cannabis plant, but with different properties and effects to cannabinoids.
- Terpenes influence the aroma and flavour of cannabis (alongside flavonoids and volatile sulphur compounds)11; cannabinoids do not.
- Terpenes are found in abundance in almost all plants; cannabinoids exist mainly in cannabis and a small number of other plants.
- Terpenes are widely available and used in a range of products including perfumes, medicines, cosmetics, and cleaning products.
- Some terpenes may interact with the endocannabinoid system, though not as strongly as cannabinoids; more research is needed in this area.6
- Terpenes can be psychoactive but are unlikely to produce the intoxicating effect commonly associated with THC.
How do terpenes influence a patient’s experience of medicinal cannabis?
Cannabis terpenes can affect a patient’s experience of medicinal cannabis in a number of ways, depending on the types, concentrations and combinations of terpenes in the flower, the cannabinoids and other compounds present, and individual patient factors.
Terpenes are highly bioactive, interacting with different receptors in the body — including cannabinoid receptors — to produce varying effects. Linalool-rich cannabis strains, for example, are likely to produce calming and pain-relieving effects beyond what isolated cannabinoids alone could achieve. Similarly, limonene-rich strains may offer greater mood elevation and antidepressant benefit than cannabinoids administered in isolation.
Mounting scientific evidence suggests that terpenes play a considerable role in modulating the intoxicating effects of THC and working in synergy with cannabinoids to potentially increase their therapeutic value. A 2018 meta-analysis of CBD treatments for epilepsy found that patients who received full-spectrum CBD extract — including cannabinoids and terpenes — experienced improved symptom control and fewer adverse effects compared to those receiving CBD isolate.12
If a medicinal cannabis treatment is selected based on cannabinoid content alone, patients may not receive the full therapeutic benefit of their treatment. Consideration of terpene profile alongside cannabinoid content is therefore an important part of optimising treatment selection.
Most commonly known cannabis terpenes
Cannabis contains more than 150 terpenes, each contributing to the plant’s therapeutic qualities. The following are among the most commonly encountered terpenes in medicinal cannabis treatments:
Caryophyllene
Found in: Black pepper, cloves, cotton
Aromas: Pepper, wood, spice, herbal
Potential uses: Pain relief, anti-inflammatory, anxiety, depression
Limonene
Found in: Lemon, fruit rinds, juniper
Aromas: Citrus, lemon, orange
Potential uses: Digestion, antibacterial, stress relief
Farnesene
Found in: Chamomile, rose, potatoes
Aromas: Sandalwood, floral, wood
Potential uses: Anti-inflammatory, anti-allergy, muscle relaxant
Humulene
Found in: Sage, ginseng, hops
Aromas: Earth, wood, spice
Potential uses: Anti-inflammatory, antibacterial, appetite-suppressing
Myrcene
Found in: Mango, thyme, lemongrass
Aromas: Musk, earth, citrus
Potential uses: Anti-inflammatory, relaxing, pain relief
Terpinolene
Found in: Lilac, sage, rosemary
Aromas: Floral, herbal, pine
Potential uses: Antibacterial, anxiety, insomnia
Linalool
Found in: Lavender, coriander, mint
Aromas: Floral, sweet, woody
Potential uses: Anxiety, insomnia, pain relief
Pinene
Found in: Pine needles, rosemary, basil
Aromas: Fresh, herbal, earth
Potential uses: Bronchodilator, anti-inflammatory, anxiety
Are terpenes safe for patients?
Terpenes are legal compounds and are not listed on any prohibited drug schedule. They are ubiquitous in the plant kingdom, present in herbs, fruits, vegetables, and flowers, as well as in a wide range of everyday products including cosmetics, cleaning products, and medicines.
In their pure, concentrated forms, terpenes can cause adverse effects including dizziness and local irritation when consumed, inhaled, or applied topically — which is why undiluted essential oils should not be ingested or applied directly to skin.13 In diluted form (5% or less), terpenes are considered non-toxic and safe for use.
Are terpenes safe in cannabis?
Medicinal cannabis products are highly regulated in Australia for safety, cannabinoid and terpene content, quality, and efficacy. Any terpenes present in approved treatments have been deemed safe for human consumption. Terpenes are not known to be addictive.
Do all medicinal cannabis treatments contain terpenes?
Not all medicinal cannabis treatments contain terpenes, and not all suppliers measure terpene content from batch to batch or prioritise maintaining the plant’s terpene profile during production. This can lead to variability in therapeutic effects between batches.
Whole flower and full-plant products retain the original terpene profile of the plant. Full-spectrum and broad-spectrum extracts may have reduced terpene profiles due to extraction processes. Isolates do not contain terpenes, though some isolate-based treatments may have terpenes or terpene blends added back in post-extraction — these are known as terpsolates.
A range of environmental and cultivation factors can influence terpene levels, including light exposure, temperature, growing conditions, nutrient levels, and harvest practices. Because many terpenes are volatile compounds that evaporate readily, they are at risk of being lost during standard extraction. Growing awareness of the therapeutic importance of terpenes is driving more sensitive extraction and production methods aimed at preserving the plant’s terpene profile.
Talking to patients about terpenes
Terpene profile can be a meaningful consideration when selecting a medicinal cannabis treatment for a patient. In addition to cannabinoid content, the terpene profile of a product may contribute to its overall effect — whether sedative, calming, uplifting, or euphoric — and individual terpenes may offer specific medicinal benefits suited to the patient’s condition, such as anti-inflammatory or anxiolytic properties.
Patient preference for certain terpene profiles may also play a role in treatment adherence and overall experience, and is worth exploring in consultation.
For patients seeking to access the full therapeutic potential of the cannabis plant, prescribing a treatment with a diverse terpene profile and a broad range of phytochemical compounds is worth considering.
References
- 1. Ferber SG, et al. The “Entourage Effect”: Terpenes Coupled with Cannabinoids for the Treatment of Mood Disorders and Anxiety Disorders. Curr Neuropharmacol. 2020;18(2):87-96.
- 2. Cox-Georgian D, et al. Therapeutic and Medicinal Uses of Terpenes. Medicinal Plants. 2019:333–359.
- 3. Xu L, et al. The effects of linalool acupoint application therapy on sleep regulation. RSC Adv. 2021;11(11):5896-5902.
- 4. Astani A, Schnitzler P. Antiviral activity of monoterpenes beta-pinene and limonene against herpes simplex virus in vitro. Iran J Microbiol. 2014;6(3):149-55.
- 5. Nadjib BM. Effective Antiviral Activity of Essential Oils and their Characteristic Terpenes against Coronaviruses: An Update. J Pharmacol Clin Toxicol. 2020;8(1):1138.
- 6. LaVigne JE, et al. Cannabis sativa terpenes are cannabimimetic and selectively enhance cannabinoid activity. Sci Rep. 2021;11(1):8232.
- 7. Mukhtar YM, et al. Biochemical significance of limonene and its metabolites: future prospects for designing and developing highly potent anticancer drugs. Biosci Rep. 2018;38(6):BSR20181253.
- 8. Greay SJ, Hammer KA. Recent developments in the bioactivity of mono- and diterpenes: anticancer and antimicrobial activity. Phytochem Rev. 2015;14:1–6.
- 9. Mahizan NA, et al. Terpene Derivatives as a Potential Agent against Antimicrobial Resistance (AMR) Pathogens. Molecules. 2019;24(14):2631.
- 10. Dash DK, et al. Revisiting the Medicinal Value of Terpenes and Terpenoids. IntechOpen. 2022. DOI: 10.5772/intechopen.102612.
- 11. Oswald IWH, et al. Identification of a New Family of Prenylated Volatile Sulfur Compounds in Cannabis. ACS Omega. 2021;6(47):31667-31676.
- 12. Pamplona FA, et al. Potential Clinical Benefits of CBD-Rich Cannabis Extracts Over Purified CBD in Treatment-Resistant Epilepsy. Front Neurol. 2018;9:759.
- 13. Millet Y, et al. Toxicity of some essential plant oils. Clinical and experimental study. Clin Toxicol. 1981;18(12):1485-98.
