Ginger has been cultivated as a spice since ancient times and almost from the start people used it to aid digestion and relieve nausea, as well as using it to treat a host of other ailments. In the Middle Ages, the spice was even promoted as a prophylactic for the bubonic plague. In the late 1800s, importers of Jamaican ginger extract advertised it as a remedy for cholera, fever, headache, rheumatism, fever, and nervous disability as well as digestive issues. One product, Lyons Extract, pronounced ginger’s palliative properties as “the most effective the world has ever produced.” Its ad, in the hyperbolic tone typical of the time, boldly stated, “Nothing can be said to strengthen the confidence of medical men in regard to its great power.”

It’s not surprising, then, that pharmacists had a role in the development of ginger ale as a nonalcoholic brother to ginger beer. Thomas Cantrell, an American apothecary living in Ireland, carbonated his drink with soda water instead of yeast and began exporting the beverage to the U.S. around 1850. This established ginger ale as an American favorite. And according to legend, the Detroit pharmacist James Vernor created a blend of ginger, vanilla, and spices and left it in an oak barrel when he was called off to fight in the Civil War. When he returned, he was delighted by the flavor, and his concoction became a hit in the Midwest. Vernor’s, a fizzy soda with a strong ginger kick, claims to be the oldest ginger ale in the U.S. And in 1904 yet another pharmacist, a Canadian named John J. McLaughlin, created a paler, dryer ginger ale—one that appealed to those who were put off by the sweetness and pungency of Vernor’s. Thus Canada Dry was born.

Ginger ale was the most popular soda in the U.S. from the late 19th century until World War II—and especially during Prohibition, as it was an ideal mixer for illicit liquor. Customers would pay 35 cents for a 12-ounce bottle when other carbonated beverages fetched a nickel. Greta Garbo’s first spoken line in the 1930 film Anna Christie, was an order for whiskey with ginger ale on the side. (“And don’t be stingy, baby!” she demanded.)

People turned to ginger ale, just as they did to ginger root earlier, when they were feeling under the weather. They continue to do so, even though “it’s questionable whether they actually have ginger contained within the beverage,” said Brett White, a physician at Southern California Kaiser Permanente Medical Group who has written about ginger’s health benefits. “If you actually look at the ingredients, it may not have ginger listed.”

Canada Dry ginger ale says it’s made with “real ginger” on the label. Chris Barnes, a spokesman for Dr. Pepper Snapple Group, which owns Canada Dry and Schweppe’s (another brand of ginger ale), says the sodas do contain real ginger, but the company won’t reveal how much to protect proprietary formulas.