Borneol is a bicyclic organic compound and a terpene derivative, which can be found in several species of Heterotheca, Artemisia, Callicarpa, Dipterocarpaceae, Blumea balsamifera and Kaempferia galanga. The hydroxyl group in this compound is placed in an endo position. The exo diastereomer is called isoborneol. Being chiral, borneol exists as enantiomers, both of which are found in nature. Whereas d-borneol was the enantiomer that used to be the most readily available commercially, the more commercially available enantiomer now is l-borneol, which also occurs in nature.

It has potential anticancer, antibacterial and antiinflamation effects. Borneol is known for its ability to enhance the permeability of cell membranes. This property has been exploited in pharmacology to improve the absorption of certain drugs, especially those with poor bioavailability. Borneol acts as a penetration enhancer and can facilitate the delivery of drugs through the skin or mucous membranes. Some studies suggest that borneol may have neuroprotective effects. It has been investigated for its potential in the treatment of neurological disorders such as Alzheimer's disease. Its ability to cross the blood-brain barrier makes it a valuable candidate for drug delivery to the central nervous system.