All true tea leaves from the Camellia sinensis tree, including black, green, oolong and white varieties, contain 30 to 90 milligrams of caffeine per 8-ounce cup. Even decaffeinated teas contain 1 to 20 percent of the tea's original caffeine content.
Most herbal teas, which are made with materials from different plants, do not contain caffeine unless it is added during the manufacturing process. Herbs with naturally occurring caffeine include guayusa, yaupon or yerba maté, from the Aquifoliaceae family, and guarana. As of 2014, most manufacturers list the caffeine content of their products on packaging and on company websites. Those with caffeine sensitivity should read labels carefully and contact the manufacturer directly to determine the actual caffeine content of tea products.