Eugenol
Eugenol is a colorless or yellowish oil used primarily as a fragrance ingredient in cosmetics, imparting a spicy scent. It is naturally found in clove, basil, and cinnamon oils. Its official CosIng functions are listed as denaturant, perfuming, and tonic. It is subject to EU Cosmetic Restrictions (III/71).
Eugenol is used in cosmetics mainly for its spicy fragrance character rather than direct skin benefits. No established skin-benefit claims are supported by the source.
Eugenol is one of the "EU 26 fragrances" that must be labelled separately on cosmetic products due to its allergen potential. A 2006 in-vitro study found eugenol to be cytotoxic to human skin cells even at very low concentrations (0.03%). The source recommends avoiding it, at minimum, in leave-on products.
