Unicum is a Hungarian herbal bitters, drunk as a digestif and apéritif. Unicum is an herbal digestif liqueur. The liqueur is today produced by Zwack according to a secret formula of more than forty herbs, and the drink is aged in oak casks. During the Socialist regime in Hungary, the Zwack family lived in exile in New York and Chicago, and during this time, Unicum in Hungary was produced using a different formula.