Zero sugar + zero calories. Monster Citron is not named after a funky looking French car or a Scandinavian vodka. The citron fruit is an ancient relative of modern lemons, but with a more primitive, aggressive nature perfect for Monster. So in homage to all ancestors both botanical and human, Ultra Citron, a new take on a classic drink. Ultra Citron's a little sweet, a little tart, light, crisp and totally refreshing. All this with zero calories, zero sugar and a full load of our Monster energy blend. Unleash the ultra beast! www.monsterenergy.com. Facebook. Instagram. Twitter. YouTube. Contains no juice. Caffeine from all Sources: 76 mg per 8 fl oz serving (152 mg per can).