Made with the leaves of wormwood — and mixed with green anise, fennel and other medicinal herbs — this high-alcohol liquor was invented by the Swiss in the 18th century, before quickly spreading into France. Pablo Picasso, Vincent van Gogh and Ernest Hemingway were known to sip the spirit, which was cheaper than wine.
Rumors that the drink caused hallucinations began to spread (some say by the winemakers) and the drink was banned for nearly 100 years. The U.S. lifted its ban on the controversial liquor in 2007.
While it won't cause hallucinations, the thujone chemical found in wormword has been found to cause seizures, kidney failure, muscle breakdown called rhabdomyolysis, tremors, dizziness and nightmares, among other conditions. Some call the drink poison due to studies that showed a high number of deaths among mice on thujone.
But don't be too freaked out: Properly made absinthe doesn't have enough thujone to cause harm. Just make sure not to buy it on the cheap from less-than-legitimate sources.