Bitters are a form of beverage prepared with herbs and citrus, dissolved in alcohol or glycerine, and having a bitter or bittersweet flavor. There are numerous brands of bitters, which were formerly marketed as patent medicines many decades ago but are now often consumed as digestifs and flavorings in cocktails.
While bitters commonly have an alcoholic strength of up to 45%, they are normally consumed in small amounts, added as a flavoring agent.
Common ingredients in bitters include angostura bark, cascarilla, cassia, gentian, orange peel, and quinine. The flavor of both Angostura Bitters and Peychaud's Bitters derives primarily from gentian, a bitter herb. Bitters are prepared by infusion or distillation, using aromatic herbs, bark, roots, and/or fruit for their flavor and medicinal properties.