Nearly 80 essential oils (including 2 jasmine absolutes) have caused contact allergy. Fifty-five of these have been tested in consecutive patients suspected of contact dermatitis, and nine (laurel, turpentine, orange, tea tree, citronella, ylang-ylang, sandalwood, clove, and costus root) showed greater than 2% positive patch test reactions. Relevance data are generally missing or inadequate. Most reactions are caused by application of pure oils or high-concentration products. The clinical picture depends on the responsible product. Occupational contact dermatitis may occur in professionals performing massages. The (possible) allergens in essential oils are discussed. Several test allergens are available, but patients should preferably be tested with their own products. Co-reactivity with other essential oils and the fragrance mix is frequent, which may partly be explained by common ingredients. Patch test concentrations for essential oils are suggested.
From acdegroot publishing, Wapserveen, The Netherlands.
Address reprint requests to Anton C. de Groot, MD, PhD, acdegroot publishing, Schipslootweg 5, 8351 HV Wapserveen, The Netherlands. E-mail: firstname.lastname@example.org.
Conflict of interest: Anton de Groot and Erich Schmidt are the authors of the book Essential oils: Contact allergy and chemical composition (CRC Press Taylor and Francis, USA, 2016, ISBN 9781482246407), to which they refer in this article.