Eugenol is a colorless to pale yellow oily liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, basil and bay leaf. It is present in concentrations of 80–90% in clove bud oil and at 82–88% in clove leaf oil. Eugenol is used in dental preparations such as surgical pastes, dental packing, and dental cement, it may cause contact stomatitis and allergic cheilitis.

Eugenol is hepatotoxic, meaning it may cause damage to the liver. Overdose is possible, causing a wide range of symptoms from blood in the patient's urine, to convulsions, diarrhoea, nausea, unconsciousness, dizziness, or rapid heartbeat.

Isoeugenol is ultimately a chemically altered form of Eugenol that is created by heating Eugenol and changing is composition. Eugenol is a liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, and bay leaf. Often seen in beauty products for its benefits as a derivative of clove oil, thanks to clove oil's antioxidant properties, a close relative of Isoeugenol is often listed as Eugenia Caryophyllus on ingredient lists. Isoeugenol is primarily used in beauty products as a fragrance ingredient because of its spicy aroma.