What Are Terpenes in Weed? The Main Cannabis Terpenes, Explained

Terpenes are the aromatic compounds that give each weed strain its smell and flavor, from citrus and pine to earth and spice. They're found in lots of plants, not just cannabis, and research suggests they may also shape the high by interacting with cannabinoids like THC and CBD.

Beyond the citrusy, floral, woody or spicy notes they bring, terpenes appear to interact with cannabinoids, boosting or tweaking their effects. Every cannabis strain has its own terpene and cannabinoid profile, which influences the overall experience, from chilled out to euphoric.

What are cannabis terpenes, exactly?

Cannabis terpenes are aromatic compounds found in many plants, weed included, and they're behind all the different smells it gives off. Between 10% and 30% of the compounds in cannabis resin are terpenes, and they're made mostly in the plant's trichomes, the tiny resin glands that frost the buds.

These compounds don't just give weed its signature aromas; they also play a crucial role in the plant's natural defenses. Unlike cannabinoids, which have no smell or taste of their own, terpenes are responsible for the citrusy, floral, earthy and woody notes in cannabis.

What do terpenes do in cannabis buds?

Since plants can't get up and walk away from predators or harsh conditions, they've evolved a defense strategy based on chemical warfare. Terpenes help plants in several ways: some repel predators, others slow their growth or mess with their metabolism.

Some cannabis terpenes also attract pollinators, or even the predators of the plant's enemies, which helps it survive. Others are produced in response to stress, like extreme heat, and help the plant adapt to its environment.

Terpenes and aromatherapy

Terpenes are the main components of the essential oils of many plants. Those oils are used in aromatherapy for their reputed therapeutic properties. For example, lavender essential oil, rich in terpenes, is used to relax, while rosemary oil is said to sharpen focus and give a sense of well-being.

You can also extract cannabis essential oil through steam distillation. It's used to make perfumes, cosmetics, candles and soaps, and as a flavoring in food and drinks.

How many terpenes are in weed?

More than 100 different terpenes have been detected in cannabis, each varying in composition and concentration. The classic citrus smell, for example, comes from limonene, but how much of it a plant has varies from one to the next.

And although the limonene in lemons and oranges is chemically very similar, small differences in molecular structure and concentration give each its own distinctive smell.

What happens to terpenes when you dry weed?

In freshly harvested cannabis, 80-90% of the essential oil is made up of monoterpenes, which are highly volatile and evaporate fast during drying. Once the plant is dry, essential oil content drops to around 0.1%, and the much less volatile sesquiterpenes take over.

Understanding terpenes isn't just key to understanding the effects and aromas of each strain. It also opens doors in aromatherapy, cosmetics and food and drink, proof that these compounds matter well beyond simply enjoying your weed.

The main types of cannabis terpenes

Myrcene

Myrcene is the most common terpene across cannabis strains, making up as much as 60% of the essential oil in some of them. It's also found in hemp, usually in lower amounts.

Outside of weed, myrcene shows up in plants like hops and the West Indian bay tree. Its aroma is earthy and musky with a hint of clove, which gives certain strains their characteristic earthy, spicy smell.

On the medical side, myrcene is being studied for pain-relieving, anti-inflammatory and antibiotic properties. Lab research also suggests it may block the action of carcinogens like aflatoxin B.

Myrcene is also associated with relaxing, calming and sedating effects, which is why it's often linked to stress relief and that couch-lock feeling. Its most talked-about trait is a possible synergy with THC: many growers and users believe it amplifies THC's psychoactive effects, though that hasn't been firmly proven.

Limonene

Limonene is another major cannabis terpene, often ranking second, third or fourth in concentration in a plant's resin. It's responsible for the fresh citrus smell we associate with lemons and oranges. Beyond its distinctive aroma, limonene has shown antifungal, antibacterial and potential anticancer properties in lab studies.

Early research suggests it may help protect against damage to the RAS gene, which is linked to tumor development, and against the Aspergillus fungus and carcinogens in smoke.

Limonene can also cross the blood-brain barrier quickly, which lets it act on the body fast. In studies on limonene, participants reported more attention, mental focus and well-being, and even a higher sex drive.

In some small studies, inhaled limonene has been explored for depression and anxiety. Research also suggests it may reduce stomach acid and support the immune system.

Caryophyllene

Caryophyllene (beta-caryophyllene) is a terpene commonly found in spices like black pepper, cloves and other herbs. Its aroma is spicy and peppery, and in cannabis it's best known for its potential anti-inflammatory and pain-relieving effects.

What makes this terpene interesting is that it can selectively activate CB2 cannabinoid receptors, which makes it a promising target for medical research. It isn't a cannabinoid, but its interaction with CB2 receptors opens the door to possible therapeutic uses for pain and inflammation.

Pinene:

Pinene is the cannabis terpene behind the fresh, resinous smell we associate with pine and fir trees. It's also found in plants like sage and rosemary. It's being studied as an expectorant, bronchodilator, anti-inflammatory and local antiseptic.

Pinene's standout trait is that it can cross the blood-brain barrier and, in lab research, inhibit acetylcholinesterase, an enzyme that breaks down a key memory messenger, which is why it's linked to better memory. In traditional medicine, plants like rosemary and sage have been prized for centuries for their brain-boosting reputation, thanks in large part to pinene.

Terpineol

Terpineol is a terpene with a floral aroma reminiscent of lilac, apple blossom and linden. It's been observed to have a sedative effect, which may partly explain why some strains feel so relaxing.

In mouse studies, exposure to terpineol cut the animals' movement by 45%, pointing to a strong relaxing effect.

Borneol:

Borneol is a terpene with a fresh, minty, camphor-like aroma. It's used in traditional Chinese medicine for fatigue and stress and to help people bounce back after an illness. Some strains, like Super Silver Haze, are reputed to be high in borneol, which users associate with a relaxing, slightly psychedelic high.

Linalool:

Linalool is a terpene with a soft floral aroma, a lot like lavender. It's known for calming, anti-anxiety effects and has been used for issues like anxiety and insomnia.

In mouse studies, it cut activity by 75%, which points to a strong relaxing effect. Linalool is also being studied for pain-relieving and anti-seizure properties, and researchers are exploring its potential against certain types of cancer.

Eucalyptol:

Eucalyptol, also known as 1,8-cineole, is the main component of eucalyptus essential oil. It shows up in small amounts in cannabis and has been linked to pain relief, sharper focus and a sense of inner balance.

Nerolidol:

Nerolidol has a woody, earthy aroma and is found in plants like ginger and citronella. In lab research it has shown antifungal, antimalarial and anti-leishmaniasis activity, and it's associated with a noticeable sedative effect.

Weed's endless list of terpenes

Cannabis resin holds plenty of other terpenes too, like phellandrene, humulene and bisabolene. Each one brings its own mix of aromas and effects, and some work in synergy with other compounds while others may counteract them.

The interplay between terpenes and cannabinoids like THC appears to shape both the experience and the potential therapeutic benefits of cannabis.