Eucalyptol

Eucalyptol, also called 1,8-cineole, is the dominant compound in eucalyptus oil and gives it its fresh, camphor-like smell and spicy, cooling taste. It was named in 1870 after Eucalyptus globulus and also makes up large shares of camphor laurel and Spanish sage oils, according to Wikipedia. PubChem notes its use in mouthwashes, cough suppressants, insect repellents and flavorings. In cannabis it is usually a trace terpene and does not feature among the main terpenes of any strain in this guide.

Unlike most terpenes on this list, eucalyptol has been tested in people as an isolated compound. Reviews by Juergens (2014) and a 2020 review in Advances in Therapy describe its mucolytic and anti-inflammatory action in the airways and cite clinical trials suggesting benefits as an add-on therapy in COPD and asthma, alongside laboratory evidence that it dampens inflammatory signaling in human immune cells. Those findings concern standardized pharmaceutical doses, not cannabis.

Wikipedia also records safety cautions: concentrated eucalyptol should not be swallowed except in highly diluted form, and should not be used on the skin during pregnancy or on children under two. PubChem lists its boiling point at about 176–177 °C.