Safety testing on essential oils has shown minimal adverse effects. Several oils have been approved for use as food additives and are classified as GRAS (generally recognized as safe) by the U.S. Food and Drug Administration; however, ingestion of large amounts of essential oils is not recommended. In addition, a few cases of contact dermatitis have been reported, mostly in aromatherapists who have had prolonged skin contact with oils in the context of aromatherapy massage. Some essential oils (e.g., camphor oil) can cause local irritation; therefore, care should be taken when applying them. Phototoxicity has occurred when essential oils (particularly citrus oils) are applied directly to the skin before sun exposure. One case report also showed airborne contact dermatitis in the context of inhaled aromatherapy without massage. Often, aromatherapy uses undefined mixtures of essential oils without specifying the plant sources. Allergic reactions are sometimes reported, especially following topical administration. As essential oils age, they are often oxidized so the chemical composition changes. Individual psychological associations with odors may result in adverse responses. Repeated exposure to lavender and tea tree oils by topical administration was shown in one study to be associated with reversible prepubertal gynecomastia. The effects appear to have been caused by the purported weak estrogenic and antiandrogenic activities of lavender and tea tree oils. Therefore, avoiding these two essential oils is recommended in patients with estrogen -dependant tumors. However, this is the first published report of this type of adverse effect when using products containing tea tree or lavender oils.
- Bilsland D, Strong A: Allergic contact dermatitis from the essential oil of French marigold (Tagetes patula) in an aromatherapist. Contact Dermatitis 23 (1): 55-6, 1990. [PUBMED Abstract]
- Schaller M, Korting HC: Allergic airborne contact dermatitis from essential oils used in aromatherapy. Clin Exp Dermatol 20 (2): 143-5, 1995. [PUBMED Abstract]
- Henley DV, Lipson N, Korach KS, et al.: Prepubertal gynecomastia linked to lavender and tea tree oils. N Engl J Med 356 (5): 479-85, 2007. [PUBMED Abstract]