This essential oil has become one of the most commonly used nonprescription remedies for mucocutaneous disorders. TTO active compounds include terpinenes such as cineole. The monoterpene terpinen is the major sensitizing compound in TTO which has become one of the most common contact allergens. The terpene alcohols such as terpin in -4-ol are the major constituents comprising 40% of TTO. They reduce histamine induced edema and wheal volume in type I hypersensitivity reactions. TTO does not have antioxidant activity nor does it suppress neutrophil superoxide. Its wide antimicrobial spectrum includes Propionobacterium acnes, Escherichia coli, Staphylococcus aureus, Herpes simplex, Candida albicans, Trichophyton dermatophytes and Sarcoptes scabeii (3,54,55).
Multiple double-blinded clinical trials document that TTO effectively treats acne and fungal/yeast infections. TTO failed to effectively treat atopic dermatitis and CVI (3,22,55).
TTO is cytolytic to epithelial cells and fibroblasts so it should not be used for burns. Photodamaged TTO is a stronger sensitizer and has induced erythema multiforme with topical application. Thus, the use of TTO in cosmeceuticals for sun exposed tissue is not scientifically sound (55).