Camphor

Aromatic substance obtained from the wood of a tree common in Southeast Asia, Cinnamomum camphora, or produced synthetically. When applied to the skin, camphor produces a cooling effect that can cause skin sensitivity with repeated use. Inhalation of camphor in concentrations of 2 ppm (parts per million) or more may cause sensitivity in the mucous membranes. Camphor can also cause skin and eye sensitivity on contact. https://www.paulaschoice.com/ingredient-dictionary/ingredient-camphor.html?q=Camphor&fdid=ingredients