Much if not all of absinthe's reputation as being somehow more insidious than other quaffable distillates arose due to adulerants and improper distillation characteristic of cheaper brands of the liquor during its latter-19th Century/early 20th Century heyday. Apart from the questionable alcohol and harmful alduterants present in some popular brands of absinthe before WWI, the terpene thujone, a component of wormwood and some other botanicals, a contributor primarily to the subtly unique flavor of absinthe as compared to other anise-flavored liquors and liquers, has been identified as having physioneurologic effect. In higher concentrations than would be found in any potable, it is a known convulsant, and can have other psychotropic effect. An article from the pharmacologic journal Current Drug Discovery
, reproduced here[/b]
discusses all this at some detail.
The fact the stuff has comparatively high alcohol content - commonly above 100 proof as compared to the more typical 80 or 86 proof of other hard liquors on the general market, and that it tastes good, is very smooth, and has a crisp, refreshing aftertaste along with a very appealing bouquet prolly is why it kicks your butt before you know what its doing the way it does.