Terpenes in cannabis: aroma, function and state of research

What terpenes are

Terpenes are volatile organic compounds that occur in many plants and are particularly abundant in cannabis. They are formed in the trichomes (resin glands) and shape the characteristic aroma of a strain – from lemony through earthy to spicy. Over 200 different terpenes have been described in cannabis, although only a handful occur in appreciable amounts.

Terpenes are what makes strains distinguishable by smell. Whether and how strongly they also influence the effect of cannabis in humans is a separate question that science has not yet settled – more on this below.

The role of terpenes in the plant

Unlike their effect in humans, their biological function in the plant is well understood. Terpenes serve:

the defence against herbivores and microorganisms,
protection against UV radiation and drying out,
the attraction of pollinators through scent signals,
the response to stress such as heat or nutrient deficiency.

The aroma of a bud is therefore no coincidence but the result of these protective and signalling functions.

The most common terpenes and their aroma

The following overview describes the aroma profile – the most reliable, well-documented property. The literature sometimes also attributes pharmacological effects to them; however, these are predominantly preclinical (cell culture, animal model) and are not the same as an established effect in humans.

Terpene	Aroma profile
Myrcene	earthy, musky, forest floor, clove
Limonene	zesty and lemony, orange blossom, fruity
Pinene (α/β)	piney, resinous, rosemary, juniper
Linalool	floral and sweet, lavender, slightly spicy
β-Caryophyllene	spicy and peppery, clove, woody
Humulene	hoppy, dry and woody, bitter and spicy
Terpinolene	floral and citrusy, lilac, sweetish
Farnesene	fruity and sweet, apple, pear

The individual terpenes with an established connection – such as myrcene and farnesene – are covered in depth in their own articles.

What is established about the effect – and what is not

A widespread idea is that terpenes specifically “modulate” the effect of cannabinoids – for example that myrcene intensifies the sedation caused by THC. This assumption is the core of the so-called entourage effect. The state of research is more sobering than the popular account suggests:

In controlled in-vitro studies, the six most common cannabis terpenes did not change the THC signal at the CB1 and CB2 receptors (Santiago et al., 2019), confirmed at the same receptors (Finlay et al., 2020) and at the ion channels TRPV1/TRPA1 (Heblinski et al., 2020).
A documented exception is β-caryophyllene, which binds directly to the CB2 receptor (Gertsch et al., 2008) – a real molecular effect, but one that concerns β-caryophyllene as an active compound in its own right, not an “enhancement” of THC.
In the opposite direction, animal models showed that individual terpenes can act in a cannabinoid-like way, though via mixed mechanisms and at high concentrations (LaVigne et al., 2021).

In addition, many terpenes have low bioavailability and are broken down quickly, so it is questionable whether they reach effective levels in the body at all.

In short: terpenes are not pharmacologically meaningless, but a general “terpene enhances cannabinoid” synergy at the classic receptor is currently not established. The full assessment is in the article on the entourage effect.

Classification

Well established: terpenes determine aroma and fulfil clear functions in the plant.
Established for individual cases: β-caryophyllene binds to CB2.
Not established: a general modulation of cannabinoid effects at CB1/CB2.
Open: possible pathways of action beyond the classic receptors.

This article describes aroma, function and the state of research and is not medical advice. Attributed effects come partly from preclinical studies and are no guarantee of an effect.