Absinthe thujone is the chemical present in Absinthe’s vital ingredient, the plant called Common Wormwood, or Artemisia Absinthium to give it its botanical name. The compound thujone was partly responsible for Absinthe being banned in early 1900s in many countries across the globe and thujone is still tightly regulated today www.absinthesupreme.com, particularly in the United States (or states united).
Thujone was regarded as similar to THC present in cannabis and Absinthe was purported to be psychoactive and have psychedelic effects causing hallucinations and insanity. Absinthe was favored by the Bohemian set in Montmartre in Paris and several artists and writers claimed that Absinthe, the Green Fairy, gave them inspiration in addition to their genius. Well-known Absinthe drinkers include Oscar Wilde, Ernest Hemingway, Van Gogh, Gauguin, Degas, Baudelaire and Verlaine. Some say that Van Gogh’s madness was due to Absinthe and that he cut off his ear under its effect 
. Absinthe was even held responsible for a man murdering his family, despite the fact that he had used a number of other strong alcoholic drinks following the Absinthe.
Prohibition campaigners used news of the murder to campaign for the outlawing of Absinthe and blamed France’s growing problems of alcohol dependency to the emerald liquor.
Is Absinthe Thujone Hazardous?
Today’s research suggests that it was in fact the alcohol (ethanol) content of Absinthe which was dangerous instead of the thujone. Absinthe is two times as strong as spirits like whisky and vodka and can be 75% alcohol. Care should therefore be taken when consuming Absinthe. Thujone is merely contained in minute quantities and must therefore cause no major side effects or health problems. The EU stipulates that alcohol based drinks with an ABV (alcohol by volume) level over 25% may possibly contain a maximum of 10mg/kg of thujone, beverages classed as “bitters” can contain up to 35mg/kg, it is not entirely clear which class Absinthe suits but most brands of Absinthe have much less than 35mg with a lot of being under 10mg/kg. In the US it is only legal to buy or sell Absinthes with trace levels of thujone.
High doses of thujone could be dangerous leading to convulsions nevertheless you will have to drink a substantial amount of Absinthe to consume that volume of thujone and it might be impossible to drink that amount, you would be comatosed from alcohol until then!
Absinthe Ingredients
It is said that Henri-Louis Pernod, who owned the very first Absinthe distillery, utilized the herbs wormwood, aniseed, fennel, lemon balm, hyssop, angelica root, dittany, star anise, nutmeg, juniper and veronica to produce his famous Pernod Absinthe. The essential oil from these herbs is mainly responsible for La Louche, the clouding which comes about when water is put into Absinthe. These herbs particularly the aniseed and anise are responsible for the distinctive aniseed or licorice taste of Absinthe and wormwood is mainly responsible for the bitter flavor. Absinthe is sometimes used as bitters in cocktails.
There are several brands of Absinthe or Absinthe substitutes that were developed over the ban and so contain no Absinthe thujone or wormwood, however, many would say that Absinthe is not Absinthe without Absinthe thujone and the bitter taste of wormwood. If you wish real Absinthe look for brands that contains wormwood or Absinthe thujone.