Eucalyptus oil is used commonly as a decongestant and expectorant for upper respiratory tract infections or inflammations, as well as for various musculoskeletal conditions. The oil is found in numerous over-the-counter cough and cold lozenges as well as in inhalation vapors or topical ointments. Veterinarians use the oil topically for its reported antimicrobial activity. Other applications include as an aromatic in soaps or perfumes, as flavoring in foodstuffs or beverages, and as a dental or industrial solvent. High quality scientific evidence is currently lacking.
Eucalyptus oil contains 70-85% 1,8-cineole (eucalyptol), which is also present in other plant oils. Eucalyptol is used as an ingredient in some mouthwash and dental preparations, as an endodontic solvent, and may possess antimicrobial properties. Listerine® mouthrinse is a combination of essential oils (eucalyptol, menthol, thymol, methyl salicylate) that has been shown to be efficacious for the reduction of dental plaque and gingivitis.
Topical use or inhalation of eucalyptus oil at low concentrations may be safe, although significant and potentially lethal toxicity has been consistently reported with oral use and may occur with inhalation use as well. All routes of administration should be avoided in children.