What Is Absinthe? Ask Paul

Not unlike meat glue, absinthe is plagued with rumor and misinformation. Let’s look at some facts.

Absinthe is a distilled spirit flavored with herbs including fennel and anise, which contribute the drink’s licorice-y flavor, and wormwood, which gives it bitterness and also its name, derived from the Latin name for wormwood, "absinthium*." The herbs, which are traditionally steeped in the spirit after it’s distilled, also give the drink its naturally green color. It became vastly popular in France and Switzerland in the late 19th century, spawning art and poetry about the spirit and its adherents, and a popular association with debauched madness.

Wormwood, and particularly a compound it contains called thujone, was considered to be the active ingredient in absinthe and blamed for hallucinations and psychosis.

In 1905, when a man murdered his family after drinking absinthe (along with a lot of other drinks), the widely publicized trial set off a bit of a panic, and within a few years, absinthe was banned in most of Europe and the United States.

For almost a century after the bans, absinthe was an obscure object of legend, and in its place, pastis was developed as a substitute and became popular in its own right. Pastis—common brands of which include Pernod and Ricard—is anise-flavored like absinthe but contains no wormwood. Pastis typically also contains sugar, which absinthe does not; instead, absinthe is sometimes ritualistically poured over a sugar cube to sweeten it.

Pastis can be substituted for absinthe in a cocktail like a Sazerac if you omit the simple syrup to compensate for pastis’s sweetness.

Straight absinthe is normally quite strong—it can be up to 160 proof—and it’s intended to be diluted with water when drinking.

Both absinthe and pastis, as well as other anise-based liquors such as ouzo and arak, put on the attractive show known as the louche—turning from clear to milky—when water is added. How does that work?

In its undiluted state, flavorful oils from the anise, which are soluble in alcohol but not in water, are dissolved in the spirit and hence invisible. But when water is mixed in, diluting the alcohol, suddenly the concentration of alcohol is too low to keep all the oil dissolved, and it emerges ("louches") in the form of microscopic droplets dispersed in the glass, scattering light and providing a magical milky appearance. 

In the early 2000s, the bans began to be repealed in Europe, and in 2007 legal absinthe became available in the U.S. for the first time since 1912—provided that it contained less than 10 milligrams of thujone per liter.

As it turns out, according to studies that have analyzed unopened bottles of absinthe from before the bans, even the original absinthes contained very little thujone. The 19th-century insanity, altered states, and crimes allegedly due to wormwood were, according to the science, attributable instead to the real psychoactive ingredient in absinthe: alcohol.

* Vermouth, another bitter herb-infused drink, also derives its name from wormwood.