Spearmint is used for its aromatic oil, referred to as oil of spearmint. The most abundant compound in spearmint oil is R-(–)-carvone, which gives spearmint its distinctive smell. Spearmint oil also contains significant amounts of limonene, dihydrocarvone, and 1,8-cineol. Unlike oil of peppermint, oil of spearmint contains minimal amounts of menthol and menthone. It is used as a flavoring for toothpaste and confectionery, and is sometimes added to shampoos and soaps.
Used as a fumigant, spearmint essential oil is an effective insecticide against adult moths.