The whole absinthe "green fairy" or whatever is just a big myth and hoax people. The "wormwood" is not going to do anything to you. There are a couple reasons why absinthe got a bad repuation and "banned".
1. The wine makers back in the day were losing money and business to absinthe, so they stated to spread rumors and blame it for mental disorders, violent crimes, epilepsy. People basically used to drink decent amounts of wine, but were now instead drinking huge quantities of absinthe. Taking moeny away from wine makers and also making people drunk as crap b/c they were not used to the high alcohol content.
2. There were stories where they would pour the absinthe through a sugar cube, but the sugar cube also contained Opium. The Opium caused the weird effects, not the wormwood.
3. The final straw was - In 1905, it was reported that Jean Lanfray, a Swiss farmer, murdered his family and attempted to take his own life after drinking absinthe. The fact that Lanfray was an alcoholic who had consumed considerable quantities of wine and brandy prior to drinking two glasses of absinthe was conveniently overlooked or ignored, therefore placing the blame for the murders solely on absinthe. The Lanfray murders would prove to be the tipping point in this hotly debated topic, and a subsequent petition to ban absinthe in Switzerland collected more than 82,000 signatures. A referendum was subsequently held on banning the drink on 5 July 1908. After it was approved by voters, the prohibition of absinthe was then written into the Swiss constitution.
So yes, you can buy "real absinthe" in the US, but it isn't going to make you see things. It's just a strong liquor that tastes like anise and fennel.