Wintergreen oil is produced from the leaves of the gaultheria procumbens, a shrub that is known by many names, including wintergreen, teaberry, boxberry, deerberry, checkerberry, spice berry, wax cluster and partridgeberry. Most commonly used as a food flavoring, wintergreen oil often is used in candy, chewing gum, mouthwash, toothpaste and other mint-flavored products. It frequently is used as a traditional herbal remedy and is a component of many over-the-counter treatments as well.
Although technically referring to the gaultheria procumbens, the word “wintergreen” is often used as a synonym for “evergreen,” referring to plants that remain green throughout the year. Wintergreen is a small shrub, standing about 5 or 6 inches (12.7 to 15.2 cm) tall. The plant is native to the northern and eastern portions of North America and grows primarily in woodlands. It flowers in late summer, producing white or pink flowers, with bright red fruits soon following. The leaves and berries of the wintergreen are edible.
Early American Indians are known to have used the fruit and leaves of the wintergreen for medicinal purposes, treating pain and respiratory complaints. Used in teas or poultices or simply chewed and ingested, wintergreen was used to treat rheumatism, fever, aches and pains and to improve respiration. European settlers also turned to wintergreen as a folk remedy to treat colic, various skin conditions, cold symptoms, sore throats and tooth decay. The first recorded use of wintergreen oil as an active ingredient for a medication was in Swaim's Panacea, first available in 1820.
Leaves of the wintergreen are steam-distilled to produce the oil, a pale yellow or pinkish liquid with a strong distinctive scent. Wintergreen oil is primarily composed of methyl salicylate and is an analgesic similar to aspirin. It can, however, be toxic; a single teaspoon (5 ml) of wintergreen oil is equivalent to roughly 20 doses of aspirin and potentially is fatal. Levels of the oil used for flavoring typically are no greater than .04 percent. Most often, the oil is used topically in over-the-counter liniments or inhaled as vapors to treat congestion.
Wintergreen's similarities to aspirin mean that people allergic to that drug should avoid wintergreen oil. People taking warfarin or blood-thinning agents also should avoid the oil. Undiluted wintergreen oil can be very dangerous if ingested or absorbed through the skin, even in small doses. Excessive levels of the oil can trigger nausea, tinnitus and vomiting; other possible outcomes include excessive bleeding, kidney and liver damage or even death. Anyone experiencing side effects from any medication, including wintergreen oil, should seek immediate medical attention.