Thujone is an active ingredient in Sage, Wormwood, Mugwort, Yarrow, Tansy, Oregano, Juniper, Cypress, Mint, and Arborvitae (genus Thuja). Thujone has a molecular shape similar to THC but is not experientially as safe. Thujone seems to build up in the body and there are reports of overdose convulsions, insomnia, or vivid dreams after a month of small amounts. As a GABA neuron regulator inhibitor in our nervous system, it has immune-system stimulating effects and as a 5-HT antagonist it may be used to treat irritable bowel syndrome. By causing neurons to fire more, it may have an inspirational effect. Mugwort pillows are supposed to bring pleasant dreams, perhaps from small airborne particles of thujone. Thujone has a fresh odor like menthol. Even though it is best known as a chemical compound in the spirit absinthe, recent tests show absinthe contains only small quantities of thujone, and may or may not be responsible for absinthe’s reported psychedelic effects.
Those with allergy to pollen may have an allergic reaction; additionally there is some evidence that it somehow over-stimulates the uterus in pregnant women which can lead to abortion. Testing is not conclusive yet. Mugwort is completely FREE and LEGAL and not lethally toxic or poisonous (with possible exception of fetuses). But, to be safe, women should not use mugwort while pregnant.