Nerolidol and Guaiol: The Woody Terpenes Explained

Most terpene talk circles around myrcene, limonene and pinene, the light, fast-fading molecules that hit your nose first.

Nerolidol and guaiol are heavier and quieter. Both are sesquiterpene alcohols, 15-carbon molecules with ties to wood: nerolidol smells of fresh bark, and guaiol is best known from wood oils. Both also have a longer record in perfume and food flavoring than in cannabis science.

Key takeaways

• Nerolidol is a sesquiterpene alcohol with a woody, fresh-bark aroma, used as a food flavoring and in perfume.
• In mice, nerolidol had a sedative effect, and in lab tests it slowed Leishmania parasites.
• Guaiol is a crystalline sesquiterpene alcohol found in guaiac wood oil and cypress pine.
• In lab tests, guaiol deterred mosquito bites about as well as DEET and killed several insect pests.
• In cannabis studies, guaiol is linked to Indica-labeled and Afghan-type plants.
• No human trial has tested either terpene, so effect claims on strain menus go beyond the evidence.

Nerolidol, the fresh-bark terpene

Nerolidol is a colorless liquid found in the essential oils of many plants and flowers, and the aroma of nerolidol is woody and reminiscent of fresh bark, according to Wikipedia. A 2016 review in the journal Molecules adds a floral side to that description.

Plenty of plants make nerolidol. This terpene helps them build a volatile compound that protects them from plant-eating insects and animals, the same review explains. Common flowering sources include:

• Lavender
• Neroli, the essential oil from bitter orange blossoms
• Lemongrass
• Tea tree
• Ginger

The Molecules review also lists cardamom and bitter melon among the plants rich in essential oils that contain it.

Most people have already met nerolidol. It is used as a flavoring agent and in perfumery, as well as in detergents and cleansers, and the U.S. Food and Drug Administration permits it as a food flavoring. In 2007, a World Health Organization food additive committee found no safety concern at current levels of intake.

Sedation, parasites and other nerolidol effects

Most of what is known about nerolidol effects comes from mice and lab dishes. In a 2013 mouse study, nerolidol showed sedative effects in animals subjected to the open field test, a standard measure of how much mice move and explore, at injected doses of 25 to 75 mg/kg. The treated mice also showed less oxidative damage in the hippocampus, a brain region tied to memory.

Other lab findings:

• In lab dishes, it slowed several species of Leishmania, the parasite behind the skin disease leishmaniasis, and cut infection in immune cells by 95%.
• In infected mice, it shrank skin lesions, though it did not cure the disease.
• As a skin penetration enhancer, it raises the rate at which several drugs pass through skin by more than 20 times.
• Lab research also points to antimicrobial and anti-inflammatory activity.

None of this has been tested in people. We found no human trial of nerolidol for sleep, anxiety or infection, and doses injected into a mouse say little about what a few puffs of cannabis deliver.

Guaiol, a crystal from wood oils

Guaiol is a sesquiterpenoid alcohol found in several plants, especially in the oil of guaiacum and cypress pine. Unlike nerolidol, the guaiol terpene is a crystalline solid at room temperature and melts at 92°C, about 198°F. In the lab, it turns deep purple when treated with certain bromine reagents.

Its best-known source has a confusing name. Oil of guaiac is a fragrance ingredient used in soap and perfume, but it comes from the palo santo tree Bulnesia sarmientoi, not from guaiacum. Steam distillation of the wood and sawdust gives an oil made of 42% to 72% guaiol and related compounds, with a soft, rose-like scent close to tea roses or violets. That resemblance is why it has been used to stretch expensive rose oil, and it is considered non-irritating and non-sensitizing to human skin.

Cypress pine, a group of trees mostly native to Australia, supplies the other half of the story. Its light, aromatic wood resists termites, and the trees are now used to make a blue essential oil rich in guaiol and chamazulene, the compound behind the blue color.

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Insects, cancer cells and guaiol

Guaiol research centers on pests. A 2013 study in Natural Product Communications pulled it from the plant Ferula ferulaeoides, where it made up 37% of one extract, and found that guaiol showed significant inhibition of aphids at a concentration of 70 mg/L. It also killed armyworm larvae on contact and worked as a fumigant against house flies. Mosquitoes avoid it, too. In a 2015 study of sage oils, pure guaiol deterred mosquito bites about as well as DEET at the same tested dose.

Cancer research is at an earlier stage still. In a 2016 study in Oncotarget, guaiol slowed the growth of non-small cell lung cancer cells in lab dishes and in mice by lowering levels of RAD51, a protein the cells use to repair broken DNA. Like nerolidol, guaiol has no human trials behind it.

Side by side, the two terpenes compare like this:

Where they show up in cannabis

In cannabis, guaiol is the better documented of the two. A 2021 Nature Plants study of more than 100 cannabis samples, tested for terpenes and cannabinoids and genotyped, found that Indica labels were linked to three sesquiterpenes: guaiol and two forms of eudesmol. An earlier study cited in the paper had tied the same three compounds to plants from Afghanistan, considered the home region of Indica cultivars, and a Dutch analysis of 460 cannabis samples in 2016 also found guaiol and the eudesmols strongly associated with the Indica type.

The 2021 study also showed why strain labels mislead. Its authors concluded that Sativa and Indica labels do not reflect genetic relatedness, and that the main differences between them may come down to a small set of terpenes.

Nerolidol is harder to measure. The Dutch team noted that the compound they took for nerolidol may have been alpha-gurjunene, another sesquiterpene. Its best-known cannabis link comes from a 2018 survey of medical cannabis patients who rated strains for anxiety relief, which found statistically significant correlations with increased anxiolytic activity for THC and trans-nerolidol. Three of the four strains patients rated best were Kush varieties high in trans-nerolidol, while guaiol appeared only in the least effective ones, at 0.05% to 0.15%. The authors suggested guaiol may be just a chemical marker and called for more research.

That survey is about as far as the evidence goes. A 2023 review of the entourage effect, the idea that terpenes and cannabinoids boost each other, found the research in its infancy, with simple study designs and contradictory results.

Seed companies cannot promise a terpene percentage, and neither strain below lists nerolidol or guaiol on its page. Both come from the families those studies point to, though. Kush lines topped the patient survey, and guaiol keeps showing up in Afghan-type plants.

• OG Kush, a Chemdawg, Lemon Thai and Hindu Kush cross at 26% THC, has an earthy terpene profile with woody undertones and a woody pine taste.
• Bubba Kush, an Afghan Kush landrace and OG Kush cross at around 29% THC, smells of earthy spice and hash, with mocha notes on the palate.

Woody notes in the grow room

Heavier sesquiterpenes evaporate more slowly than the light terpenes that dominate a fresh harvest, but heat and air still wear them down. Nerolidol boils at 276°C, about 529°F, according to the 2016 review, so a slow dry in a cool, dark room and an airtight cure keep more of a harvest's woody side. Grinding exposes far more surface to air, so store buds whole and grind just before use.

Bark, wood and open questions

Nerolidol smells of fresh bark and flowers, flavors food and perfume, and has calmed mice and slowed parasites in lab studies. Guaiol, a crystal from palo santo and cypress pine oils, repels insects in tests and keeps turning up in Indica-type cannabis. Neither has been tested in people, and the entourage effect remains unproven, so read terpene claims on a menu as a clue to aroma, not a promise of effect.

Grow for the nose and let the science catch up. Barney's Farm has been developing premium cannabis genetics since the 1980s, with over 40 Cannabis Cup wins. Explore our full seed catalog and find strains bred for every climate and skill level.