What bitters is traditionally used in an Old Fashioned?

The traditional bitters used in an Old Fashioned is Angostura bitters. This specific type of bitters has a rich history and is known for its complex flavor profile, which includes hints of aromatic spices and herbs. The use of Angostura bitters in the Old Fashioned cocktail enhances the drink's depth and character, providing the necessary balance to the sweetness of the sugar and the strength of the whiskey.

Angostura bitters have a distinct flavor that complements the whiskey, making it a classic choice that is widely recognized and used in this cocktail. The Old Fashioned itself is a simple drink that relies on quality ingredients and essential flavors, and the addition of Angostura bitters is crucial to its traditional preparation and overall taste.