Eugenol (C₁₀H₁₂O₂), is an allyl chain-substituted guaiacol, i.e. 2-methoxy-4-(2-propenyl)phenol. It is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil and cinnamon. It's slightly soluble in water and soluble in organic solvents. It has a spicy, clove-like taste. Eugenol is used in perfumeries, flavorings, essential oils and in medicine (local antiseptic and analgesic). It was used in the production of isoeugenol for the manufacture of vanillin, though most vanillin is now produced from petrochemicals or from biproducts of paper manufacture. Eugenol has wide application in dentistry for analgesic and antiseptic properties. When mixed with zinc oxide, eugenol forms a cement used in dentistry. Eugenol derivatives or methoxyphenol derivatives in wider classification are used in perfumery and flavoring. They are used in formulating insect attractants and UV absorbers, analgesics, biocides and antiseptics. They are also used in manufacturing stabilizers and antioxidants for plastics and rubbers.

Overdose is possible, causing a wide range of symptoms from blood in the patient's urine, to convulsions, diarrhea, nausea, unconsciousness, dizziness, or rapid heartbeat.