Unicum is an herbal digestif liqueur. The liqueur is today produced by Zwack according to a secret formula of more than forty herbs; the drink is aged in oak casks. During Communism in Hungary, the Zwack family lived in exile in New York and Chicago, and Unicum in Hungary was produced using a different formula. Before moving to the US Janos Zwack had entrusted a family friend in Milan with the production of Unicum based on the original recipe. After the fall of communism, Péter Zwack returned to Hungary and resumed production of the original Unicum.
Unicum is regarded as one of the national drinks of Hungary. The production facility offers tours which include a tasting session of the three different varieties (Unicum, Unicum Next, and Millenicum). Though Millenicum was a special edition, it can still be found at a few retailers. It is somewhat stronger than the original, with a slightly sweeter aftertaste. Zwack Frissitők is a pineapple-based version of the drink. According to the manufacturer, the original Unicum is no longer distributed in the US, having been replaced by Unicum Next (a sweeter, thinner-bodied drink with a more prominent citrus flavour), re-branded as "Zwack".