Thujone is psychoactive, but not in the way most people expect. It is primarily a neurotoxin that disrupts normal brain signaling, and at high doses it can cause seizures, tremors, and possibly hallucinations. The romantic idea that it produces a pleasant, cannabis-like high, especially through absinthe, is largely a myth built on 19th-century misunderstandings and debunked science.
How Thujone Affects the Brain
Thujone works by blocking a specific type of receptor in the brain that normally keeps nerve cells from firing too rapidly. These receptors, called GABA-A receptors, act like brakes on your nervous system. When thujone blocks the chloride channels on those receptors, it removes the brakes. Neurons fire more easily and more often than they should.
This mechanism is similar to how known convulsant poisons work. The symptoms of thujone poisoning, including seizures, can be reversed by the same drugs used to treat seizure disorders, which reinforces that its main effect is overstimulating the nervous system rather than producing a controlled “high.” At toxic doses, this overstimulation leads to restlessness, vomiting, vertigo, tremors, convulsions, and in rare cases, death. People who consumed thuja oil (from a related plant) in doses as small as 20 drops per day for five days have experienced severe neurotoxicity.
Is It a Hallucinogen?
Some sources describe thujone as hallucinogenic, and there are historical reports of hallucinations in heavy absinthe drinkers. But the picture is more complicated than “thujone causes hallucinations.” The syndrome known as “absinthism,” characterized by hallucinations, sleeplessness, tremors, convulsions, and paralysis, was documented in the 1800s among people who drank large quantities of absinthe over long periods. At the time, thujone was blamed.
Modern research tells a different story. Multiple investigations have concluded that thujone played little or no role in absinthism. The real culprit was almost certainly the alcohol itself. Absinthe typically contained over 50% alcohol by volume, and heavy drinkers were consuming enormous quantities. The hallucinations and neurological damage attributed to thujone are now widely considered symptoms of severe, chronic alcohol poisoning.
That said, one controlled study in 25 healthy volunteers found that high concentrations of thujone (100 mg per liter) combined with alcohol did impair attention performance more than alcohol alone. So thujone can affect mental function at sufficient doses, but the threshold for these effects is well above what any regulated beverage delivers.
The Cannabis Connection That Wasn’t
A popular theory once held that thujone worked like THC, the psychoactive compound in cannabis, because the two molecules share some structural similarities. This idea was tested directly in the late 1990s. Researchers found that thujone does bind to cannabinoid receptors, but only at concentrations far higher than would ever occur in the human body from drinking absinthe or sage tea. More importantly, even at those extreme concentrations, thujone failed to activate the receptors in any meaningful way. It didn’t trigger the same cellular signals THC does, and rats given thujone behaved nothing like rats given cannabinoid drugs.
The conclusion was clear: thujone does not produce cannabis-like effects. Whatever psychoactive properties it has come from its role as a GABA blocker and nervous system stimulant, not from mimicking THC.
How Much Thujone Is in Absinthe
Chemical analysis of 13 authentic pre-ban absinthe bottles (made before the spirit was outlawed around 1915) found thujone levels ranging from 0.5 to 48.3 mg per liter, with an average of about 25 mg per liter. These concentrations were far lower than historical estimates suggested. Even more telling, modern absinthes made from traditional recipes contain similar amounts. The researchers found nothing in the old bottles, besides ethanol, that could explain the legendary effects of absinthe.
To put this in practical terms: you would need to drink a dangerous, potentially lethal amount of high-proof alcohol before the thujone in absinthe could reach levels that affect your brain independently. The alcohol would incapacitate or kill you long before the thujone became relevant.
Regulatory Limits on Thujone
Governments regulate thujone tightly. In the United States, foods and beverages made with wormwood, white cedar, oak moss, or tansy must be “thujone-free” in the finished product. International guidelines set maximum levels at 0.5 parts per million in food and non-alcoholic beverages, 5 ppm in lower-alcohol drinks, 10 ppm in spirits above 25% alcohol, and 35 ppm in bitters. These limits keep thujone exposure far below any dose that could produce noticeable psychoactive or toxic effects.
Where Thujone Occurs Naturally
Thujone exists in two forms, alpha and beta, and both are found in common herbs. Wormwood (the herb used to make absinthe) is rich in beta-thujone, which can make up over 50% of its essential oil. Common sage is rich in alpha-thujone, sometimes at similar percentages. You likely consume trace amounts of thujone if you cook with sage or drink sage tea.
Your liver processes thujone efficiently. After drinking sage tea containing about 575 micrograms of alpha-thujone, volunteers excreted breakdown products in their urine, showing that the body converts it into water-soluble compounds that can be eliminated. The liver uses its standard detoxification enzymes to break thujone into several less active compounds, which are then tagged for removal through urine.
Neurotoxin First, Psychoactive Second
The most accurate way to think about thujone is as a neurotoxin that happens to have psychoactive side effects at dangerous doses. It is not a recreational drug. It does not produce euphoria, altered perception, or a high at any dose that could be safely consumed. Its psychoactive effects, when they occur, are symptoms of poisoning: the kind of disordered brain activity that comes from stripping away the nervous system’s natural inhibition. The mystique around thujone comes almost entirely from the cultural mythology of absinthe, not from the compound’s actual pharmacology.