Wintergreen Oil: Evidence, Safety and How It Is Used

Urgent first. If a child or anyone may have swallowed wintergreen oil or a rub, liniment or medicated oil that contains methyl salicylate, call Poison Help at 1-800-222-1222 (US) right away; call 911 for collapse, a seizure or trouble breathing. [1] Poison Control says wintergreen oil is very dangerous if more than a tiny amount is swallowed, and that swallowing it is roughly equivalent to swallowing a large number of adult aspirin tablets. [1] A review of methyl salicylate poisoning found that in children under 6, a teaspoon (5 mL) or less of oil of wintergreen has been implicated in several well-documented deaths. [2] See Poisoning: what to do first. We do not advise swallowing wintergreen oil or any essential oil.

What wintergreen oil is

Wintergreen oil is a strong-smelling oil that is mostly methyl salicylate, a chemical related to aspirin. A review describes oil of wintergreen as 98% methyl salicylate and says methyl salicylate is also a component of many over-the-counter creams, ointments, lotions, liniments and medicated oils meant for aches and pains, including products marketed as Asian herbal remedies. [2] Poison Control says wintergreen is used in some over-the-counter skin products to relieve pain and creates a feeling of warmth. [1] Because the chemical is in so many products, the danger is not limited to bottled oil. Check the label of any pain rub.

Which plant, which part

The accepted name on GBIF is Gaultheria procumbens L., in the heath family (Ericaceae). [3] The sources we read for this page describe "oil of wintergreen" and methyl salicylate but do not say which plant part or species a given product or case involved.

Traditional use

Traditional use only, not proof: the sources we read did not describe the traditional use of wintergreen oil, so we do not describe it.

What research shows

Safety

• Poisoning, especially in children. Methyl salicylate continues to be a relatively common source of pediatric exposures, with persistent reports of life-threatening and fatal toxicity. [2] Keep every product containing it locked away.
• Warfarin and other blood thinners. A study of 11 patients taking warfarin found raised INR (a blood clotting measure) after significant use of topical methyl salicylate ointment, with bruising in 2 and gastrointestinal bleeding in 1. [5] A case report describes an INR of 12.2 in a woman whose INR had been stable on warfarin, after she used a topical pain gel on her knees daily for eight days. [6] Anyone on warfarin or another blood thinner should ask a pharmacist or prescriber before using any methyl salicylate product. Never stop or change a prescribed medicine without asking. See supplements and blood thinners and how interactions work.
• Skin absorption. Methyl salicylate is absorbed through the skin in measurable amounts. [6] A case report describes salicylate poisoning after a herbal skin cream containing methyl salicylate was used on abnormal skin under an occlusive dressing. [7] Another describes full-thickness skin and muscle necrosis and persistent kidney inflammation after topical methyl salicylate and menthol followed by a heating pad. [8] This is why product directions about covering skin and heat matter.
• Skin and allergy. Poison Control says many essential oils can cause rashes and advises not using them on damaged skin. [1]
• Pregnancy. Pregnancy and breastfeeding safety are not described in the sources we read; ask a clinician. See pregnancy and breastfeeding.
• Liver and kidney. One case above involved persistent interstitial nephritis (kidney inflammation). [8] People with kidney or liver disease should ask a clinician.
• Surgery: tell the surgical team about any methyl salicylate product, because of the bleeding reports.

Official statements

• Poison Control (US): wintergreen oil is very dangerous if more than a tiny amount is swallowed. [1]