Image by Ettore Balocchi, some rights reserved.

"The leaves and flowering tops are harvested from wild and cultivated plants. Wormwood has a penetrating, aromatic odor and a spicy, strongly bitter taste. The bitter principles contained in the aerial parts of the plant are classified chemically as sesquiterpene lactones, which occur as momomers such as artabsin or dimmers such as absinthin. Wormwood contains about 0.3- 0.5% volatile oil, up of 70% of which consists of the two stereoisomeric forms of thujone, designated as (-) -thujone and (+)-isothujone; these compounds give the herb its pleasant, fresh, spicy odor.
When the herb is taken in small doses (e.g., 1.0 g in an infusion or tincture), it acts as an aromatic bitter. As the dosage is increased, the toxic effect of the thujone becomes more pronounced, leading to increased salivation and hyperemia of the mucous membranes and pelvic viscera. The production of pure wormwood liquors is prohibited by law due to the risk of absinthe addiction. Thujone heightens and alters the effects of alcohol, and chronic thujone poisoning leads to cerebral dysfunction with epileptiform seizures, delirium, and hallucinations. Roman wormwood (Artemisia pontica) is best for making vermouth wines, as this species has a finer aroma and a much lower thujone content for better tolerance. The leaves of the maritime absinthe (Artemisia maritima) are also used in making vermouth.
The 1984 Commission E monograph on wormwood states that the crude drug (dried aerial parts) should have a minimum content of 0.3% volatile oil and a relative bitterness of at least 15,000. The monograph cites as indications poor appetite, dyspeptic complaints, and biliary dyskinesia, recommending an average daily does of 2-3 g of the crude drug."

-pp. 169- 170, Rational Phytotherapy: A Physicians' Guide to Herbal Medicines by Schulz Hansel Tyler (1998)

Absinthe, Wormwood