Wintergreen
Scientific Name(s): Gaultheria procumbens L.
Common Name(s): Boxberry, Canada tea, Checkerberry, Deerberry, Gaultheria oil, Mountain tea, Partridgeberry, Teaberry, Wintergreen
Clinical Overview
Use
In addition to being used as a flavoring, wintergreen and its oil have been used in topical analgesic and rubefacient preparations for the treatment of muscular and rheumatic pain. However, no clinical data support the use of wintergreen for any condition.
Dosing
Dosing recommendations for oral or topical administration of wintergreen oil are not available. Even small doses of oral wintergreen oil may cause toxicity.
One teaspoon (5 mL) of wintergreen oil is equivalent to approximately aspirin 7 g or 21.5 (325 mg) adult aspirin tablets.
Contraindications
Avoid oral or topical application in children. Avoid use in patients with known hypersensitivity to any components of wintergreen oil and in patients with known salicylate allergy, or GI irritation or inflammation.
Pregnancy/Lactation
Generally recognized as safe (GRAS) when used as food. Avoid dosages higher than found in food because safety and efficacy are unproven.
Interactions
Monitor for potentiation of warfarin anticoagulation in patients using methyl salicylate or topical wintergreen oil.
Adverse Reactions
Wintergreen may cause hypersensitivity reactions. Topical administration of methyl salicylate may cause redness and irritation; second- and third-degree burns have been reported rarely with menthol-methyl salicylate formulations.
Toxicology
When ingested, highly concentrated liquid methyl salicylate in the form of wintergreen oil, as with other volatile oils, can induce vomiting and cause severe, often fatal, poisonings.
Botany
Wintergreen is a perennial evergreen shrub with thin, creeping stems and leathery leaves with toothed, bristly margins. It is a low-growing plant native to eastern North America and usually found in woodland and exposed mountainous areas. Its small, waxy, white or pale pink flowers bloom in late summer, developing a scarlet fruit. The aromatic leaves and fruits are edible.Chevallier 1996, Simon 1984
History
American Indians reportedly used wintergreen for treating back pain, rheumatism, fever, headaches, and sore throats.Chevallier 1996 The plant and its oil have been used in traditional medicine as an anodyne, analgesic, carminative, astringent, and topical rubefacient. Wintergreen tea has been used to relieve cold symptoms and muscle aches.Dobelis 1986
Wintergreen oil is obtained by steam distillation of the warmed, water-macerated leaves. It is used interchangeably with sweet birch oil or methyl salicylate (typically no more than 0.04%) for flavoring foods and candy.
Wintergreen berries have been used to make pies.Duke 1985 A tea made from the leaves was used as a substitute for Camellia sinensis tea during the Revolutionary War.Chevallier 1996
Chemistry
Wintergreen oil is an extremely potent liquid form of methyl salicylate (98% methyl salicylate w/w).Chyka 2007 It is produced by macerating wintergreen leaves in warm water, followed by steam distillation.Khan 2010 During the process, gaultherin is enzymatically hydrolyzed to methyl salicylate.Howrie 1985, Simon 1984, Spoerke 1980 The yield of wintergreen oil from the leaves ranges from 0.5% to 0.8%.Khan 2010 Production of wintergreen oil by distillation from the natural product has been largely replaced by synthetic production of methyl salicylate.Bone 2013 Wintergreen oil has a distinct sweet aromatic odor and is either colorless or has a red or yellow tinge.Burdock 2010
Uses and Pharmacology
Small oral doses of wintergreen oil have been reported to stimulate digestion and gastric secretions.Duke 1985 Extreme caution is advised with this usage because dosing had not been determined and ingestion of even small amounts of wintergreen oil can cause toxicity.Chyka 2007
Topical wintergreen oil is a counterirritant that may offer some analgesic effect because of the structural similarity of methyl salicylate to aspirin. The US Food and Drug Administration lists OTC topical formulations of methyl salicylate (10% to 60%) as safe and effective for temporary relief of mild to moderate aches and pains. These formulations may also contain menthol and/or camphor and are available as gels, creams, ointments, and sprays.Olenak 2012
Animal data
Research reveals no animal data regarding the use of wintergreen.
Clinical data
Research reveals no clinical data regarding the efficacy of wintergreen for any condition.
Methyl salicylate is rapidly absorbed after oral administration of wintergreen oil.Howrie 1985 An open-label of 4 adult volunteers found that the bioavailability of methyl salicylate was greater after oral administration than after the use of methyl salicylate cream.Wolowich 2003
Topical administration of methyl salicylate results in systemic salicylate exposure.Morra 1996 Methyl salicylate also inhibits platelet aggregation, as measured in a randomized, blinded, crossover trial after administration of single doses of oral aspirin 162 mg and topical methyl salicylate 5 mg. Both treatments significantly decreased platelet aggregation compared to baseline, with no significant difference in the degree of platelet aggregation between them.Tanen 2008
Dosing
Dosing recommendations for oral or topical administration of wintergreen oil are not available. Wintergreen oil is 98% methyl salicylate. One milliliter of wintergreen oil is equivalent to 1.4 g of aspirin. One teaspoon (5 mL) of wintergreen oil 1 tsp (5 mL) is equivalent to approximately 7 g of salicylate 7 g of aspirin or the equivalent of 21.5 (325 mg) adult aspirin tablets. Even small doses of oral wintergreen oil may cause toxicity.Chyka 2007
Pregnancy / Lactation
GRAS when used as food. Avoid dosages higher than those found in food because safety and efficacy are unproven.
Interactions
Topical administration of methyl salicylate has been reported to increase the international normalized ratio (INR) with warfarin in case reports and case series, resulting in bruising, retroperitoneal bleeding, GI bleeding, and INR increases as high as 12.2. Patients using methyl salicylate or wintergreen oil should be monitored for potentiation of warfarin anticoagulation.Chan 2009, Joss 2000, Yip 1990
Adverse Reactions
One case report documents a potential hypersensitivity reaction in a nonsmoking, 21-year-old woman with a history of asthma who complained of wheezing, dry cough, and bronchial pain after using a tartar-control toothpaste flavored with wintergreen.McCarthy 1992, Toothpaste 1991 Another case report documents the development of laryngeal edema in a patient after accidental ingestion of wintergreen oil.Botma 2001 Because wintergreen oil is absorbed and converted to salicylic acid after both oral and topical administration, it should be used with caution in people with nonallergic aspirin sensitivity.Howrie 1985, Morra 1996, Olenak 2012
Wintergreen oil may cause hypersensitivity reactions, with topical administration of methyl salicylate causing redness and irritation.Olenak 2012 Second- and third-degree burns have been reported rarely with topical products containing menthol alone or menthol and methyl salicylate in concentrations greater than 3% and 10%, respectively. Most reactions occurred with 24 hours of initial application.FDA 2012
Toxicology
When ingested, the highly concentrated liquid methyl salicylate, in the form of wintergreen oil, as with other volatile oils, can induce vomiting and cause severe, often fatal, salicylate poisoning.Duke 1985, Howrie 1985
The oil may be particularly toxic to children, who may associate the pleasant odor of wintergreen oil with "candy." Wintergreen oil 5 mL is equivalent to aspirin 7 g, the same amount in 21.5 adult aspirin tablets (325 mg) (wintergreen oil 1 mL is equivalent to aspirin 1.4 g).Chyka 2007
Ingestion of as little as 4 mL in a child and 6 mL in an adult has been fatal.Chyka 2007, Dreisbach 1987, Tyler 1988 Because of this potential for toxicity, official labeling requirements have been changed so that no drug product may contain more than methyl salicylate 5%.FDA 2015 No deaths have been reported from ingestion of the plant itself.Simon 1984 The American Association of Poison Control Centers recommends emergency department referral for ingestion of more than a lick or taste of wintergreen oil (98% methyl salicylate) in a child younger than 6 years of age.Chyka 2007 Referral is also recommended for ingestion of more than wintergreen oil 4 mL in people 6 years of age and older.
Because the essential oil and its components can be absorbed through the skin, salicylate, intoxications can occur following topical application of methyl salicylate or wintergreen oil. Due to a structural similarity between methyl salicylate and acetylsalicylic acid (aspirin), a toxic syndrome similar to that seen in salicylism and characterized by tinnitus, nausea, and vomiting has been observed in people who have ingested wintergreen for prolonged periods of time.Duke 1985
A 40-year-old man became acutely ill within 1 hour after an herbalist applied an herbal skin cream containing an unknown amount of wintergreen oil for the treatment of psoriasis. Salicylate absorption may have been increased by use of an occlusive dressing. The patient developed tinnitus followed by hyperpnea, vomiting, diaphoresis, fever, and CNS disturbance (wintergreen oil in liquid form is a highly lipid soluble).Bell 2002
A 70-year-old woman, seeking relief for chronic knee pain, developed fatal clinical manifestations of methyl salicylate poisoning (eg, acid-base disturbance, endocrine abnormalities, fluid and electrolyte imbalances, CNS toxicity) after ingesting topical Koong Yick Hung Fa Oil 60 mL, which contains salicylic acid 56.2 g (the equivalent of 173 regular-strength, adult aspirin tablets).Hofman 1998
References
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