Beer does not contain caffeine unless a brewery adds it into the brew mixture. The U.S. Food and Drug Administration (FDA) does not sanction the use of caffeine in beer. American breweries are prevented from adding caffeine to beer by strict federal and state regulations.
Although beer manufacturers are not required to list ingredients used to make beer, caffeine is not a natural substance produced in the normal brewing process. The FDA considers caffeine to be a food additive, and additives are commonly regulated. Prohibiting the sale of caffeinated beer protects beer drinkers from potential adverse health effects that may arise from mixing depressants and stimulants within an alcoholic beverage.