Obtained naturally from betula, sweet birch, or teaberry oil. Present in certain leaves and bark but usually prepared by treating salicylic acid with methanol. Wintergreen extract is used in root beer and wintergreen flavorings for beverages and candy (5,000 ppm). The oil is used for checkerberry, raspberry, teaberry, fruit, nut, root beer, sassafrass, spice and wintergreen flavorings for beverages, ice cram, ices, candy, baked goods (1,500 ppm), and chewing gum (3,900 ppm). Wintergreen is a strong irritant. Ingestion of relatively small amounts may cause severe poisoning and death (average lethal dose in children is 10 milliliters and in adults 30 milliliters). Symptoms of poisoning are nausea, vomiting, acidosis, pulmonary edema, pneumonia, and convulsions. Can be fatal. Very irritating to the mucous membranes and skin and can be absorbed rapidly through the skin. Like other salicylates, it has a wide range of interaction with other drugs, including alcohol, antidiabetic medications, Vitamin C, and tranquilizers.