Lithium in 7-Up

Everyone knows that Coca-Cola was originally formulated to contain cocaine.  I didn't know that 7-Up contained lithium.

... lithium was widely marketed as one of a number of patent medicine products popular in the late-19th and early-20th centuries, and was the medicinal ingredient of a refreshment beverage, 7 Up. Charles Leiper Grigg, who launched his St. Louis-based company The Howdy Corporation in 1920, invented a formula for a lemon-lime soft drink in 1929. The product, originally named "Bib-Label Lithiated Lemon-Lime Soda", was launched two weeks before the Wall Street Crash of 1929.  It contained the mood stabiliser lithium citrate and was one of a number of patent medicine products popular in the late-19th and early-20th centuries. The beverage was marketed specifically as a hangover cure. Its name was soon changed to 7 Up.

More about 7-Up and the history of its name at Snopes.