The plant is the original source of oil of wintergreen, whose sharp, penetrating scent is almost pure methyl salicylate; the same compound is now made synthetically for flavouring and liniments. That concentrated oil is genuinely dangerous, highly toxic if swallowed even in small amounts, since a teaspoon contains the salicylate of many aspirin tablets, a fact stated here plainly as caution, not as any encouragement to use. The historical medicinal use of the mild leaf-tea is recorded as folk history only. In the modest language of plant correspondence wintergreen carries associations of protection and renewal, read from its evergreen persistence and its clean, reviving fragrance.
Because methyl salicylate is absorbed readily through the skin, modern clinical toxicology has documented genuine cases of salicylate poisoning from the overuse of wintergreen-scented liniments and muscle rubs, not only from swallowing the oil, a caution that belongs alongside the ingestion warning above. The same chemistry links wintergreen to the aspirin family of drugs, since methyl salicylate is metabolised in the body to salicylic acid, the same active principle later isolated from the willow and from meadowsweet, so that a plant valued by Native American and settler herbalists alike for easing aches was, without either group knowing why, working through the pathway modern medicine would eventually explain.