Despite having several common names that suggest Thuja occidentalis is a variety of cedar, the conifer is actually a member of the cypress family. Steam distillation of the leaves and twigs yield an essential oil with a pungent aroma and a long list of active phytochemicals. The aromatic quality of the oil is referenced by the tree’s genus name, which is adapted from the Latin word thuja and means “to fumigate.”
The strong scent of the oil is due, in part, to a high concentration (up to 65%) of thujone. Because this compound is a neurotoxin, ingesting this oil at any time is not a good idea. Pregnant or nursing women, in particular, should avoid thuja essential oil.