Schweppes tonic water is carbonated water with sweetener, preservatives, natural flavors and quinine added. It is commonly used as a mixer in alcoholic beverages, such as gin and tonic.
Schweppes tonic water is sweetened with high-fructose corn syrup and has benzoate as a preservative. The quinine adds a distinctive bitter taste. Tonic water was originally developed to prevent malaria. Modern versions, including the variety produced by Schweppes, contain less quinine than the earlier versions.
Eight fluid ounces, or one serving, of tonic water contains about 130 calories, 55 milligrams of sodium and 32 grams of sugar. Tonic water does not contain caffeine.