Patch Testing with Main Sensitizers Does Not Detect All Cases of Contact Allergy to Oxidized Lavender Oil

Abstract

Lavender oil is an essential oil obtained from lavender (Lavendula angustifolia). The main components linalool and linalyl acetate have been shown to autoxidize in contact with oxygen in the air, forming sensitizing hydroperoxides. Patients with suspected allergic contact dermatitis were consecutively patch-tested with oxidized lavender oil 6% pet., oxidized linalyl acetate 6% pet., and oxidized linalool 6% pet. to investigate the frequency of contact allergy to oxidized lavender oil, and the pattern of concomitant reactions to oxidized linalool and oxidized linalyl acetate. Positive reactions to oxidized lavender oil were found in 2.8% of the patients. Among those, 56% reacted to oxidized linalool and/or oxidized linalyl acetate, while 52% reacted to the fragrance markers of the baseline series. Oxidized lavender oil showed among the highest frequencies of contact allergy to studied essential oils. A well-standardized preparation of oxidized lavender oil could be a useful tool for diagnosis of contact allergy to fragrances.

Contact allergy to oxidized geraniol among Swedish dermatitis patients—A multicentre study by the Swedish Contact Dermatitis Research Group

“…The high frequencies of reactions to oxidized fragrance compounds in clinical testing have turned the focus to potential haptens that are formed by air oxidation from far less sensitizing materials. The clinical relevance of these reactions has been discussed, and it has been shown that the patients, if questioned, will, in many cases, be using a product containing the mother compound on the dermatitis areas . For many individuals, the dermatitis will clear when such exposure is terminated .…”

“…Analysis of pure and oxidized geraniol was conducted with external standards as previously described . Analysis of the patch test preparations was performed with solid‐phase extraction to determine the stability of the hydroperoxide, according to previous experience …”

Essential Oils and Their Single Compounds in Cosmetics—A Critical Review

“…One study using 6% oxidized lavender oil investigated the frequency of contact allergy caused by oxidized lavender oil. 2.8% of the patients had positive reactions to oxidized lavender which indicated that oxidized compounds of lavender oil are a common cause of contact allergy [35].…”

Aromatherapy and occupational allergic contact dermatitis: Two further cases caused by lavender oil and other essential oils

“…It has many useful properties, such as being fragrant, and having sedative, soothing and antimicrobial effects; it is also considered to be antidepressive and effective for the treatment of burns and insect bites . The main components of lavender oil, that is, the terpenes linalool, linalyl acetate, and caryophyllene, have been shown to autoxidize, forming sensitizing hydroperoxides . Pure lavender oil was shown to be a weak sensitizer, but the oxidized form was classified as a moderate allergen.…”

“…Pure lavender oil was shown to be a weak sensitizer, but the oxidized form was classified as a moderate allergen. Furthermore, essential oils are usually complex mixtures in which new sensitizing substances could form over time in chemical reactions between the components of the mixture; different sensitizers together could induce a stronger inflammatory reaction than a single one . Identifying the responsible allergenic component of essential oils is difficult, and, moreover, co‐sensitization to multiple perfumes and essential oils is common.…”