Absinthe thujone is the chemical found in Absinthe’s vital ingredient, the plant referred to as Common Wormwood, or Artemisia Absinthium to give it its botanical name. The compound thujone was partly the cause of Absinthe being banned in early 1900s in lots of countries across the globe and thujone continues to be tightly regulated today absinthe supreme, particularly in the United States (or states united).
Thujone was thought to be similar to THC seen in cannabis and Absinthe was speculated to be psychoactive and possess psychedelic effects causing hallucinations and insanity. Absinthe was popular with the Bohemian set in Montmartre in Paris and many 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 claim 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, even though he had ingested a number of other strong alcoholic drinks after the Absinthe.
Prohibition campaigners used news of the murder to campaign for the banning of Absinthe and blamed France’s growing problems of alcoholism to the emerald liquor.
Is Absinthe Thujone Harmful?
Today’s studies suggest that it was actually the alcohol (ethanol) content of Absinthe which was dangerous rather than the thujone. Absinthe is twice as strong as spirits like whisky and vodka and can be 75% alcohol. Care should therefore be used when consuming Absinthe. Thujone is only present in minute quantities and should therefore cause no major unwanted effects or health conditions. The EU stipulates that booze with an ABV (alcohol by volume) level over 25% may possibly have a maximum of 10mg/kg of thujone, beverages classed as “bitters” can contain as much as 35mg/kg, it isn’t entirely clear which class Absinthe matches 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 get or sell Absinthes with trace levels of thujone.
High doses of thujone may be dangerous triggering convulsions but you will have to drink a great deal of Absinthe to consume that quantity of thujone and it would be impossible to drink that amount, you’d be comatosed from alcohol until then!
Absinthe Formula
It is known that Henri-Louis Pernod, who owned the very first Absinthe distillery, used the herbs wormwood, aniseed, fennel, lemon balm, hyssop, angelica root, dittany, star anise, nutmeg, juniper and veronica to create his famous Pernod Absinthe. The essential oil from all of these herbs is responsible for La Louche, the clouding which occurs when water is put into Absinthe. These herbs specially 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 oftentimes used as bitters in cocktails.
There are lots of brands of Absinthe or Absinthe substitutes which were developed during the ban and thus 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 search for brands that contain wormwood or Absinthe thujone.