PORTLAND, ORE. – When patients present to Brandon L. Adler, MD, with dermatitis on the eyelid, face, or neck, he routinely asks them if they apply essential oils on their skin, or if they have an essential oil diffuser or nebulizer in their home.
“The answer is frequently ‘yes,’ ” Dr. Adler, clinical assistant professor of dermatology at the University of Southern California, Los Angeles, said at the annual meeting of the Pacific Dermatologic Association. “Essential oils are widely used throughout the wellness industry. They are contained in personal care products, beauty products, natural cleaning products, and they’re being diffused by our patients into the air. More than 75 essential oils are reported to cause allergic contact dermatitis.”
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“Linalool is most classically associated with lavender, while limonene is associated with citrus, but they’re found in many different plants,” said Dr. Adler, who directs USC’s contact dermatitis clinic. “On their own, linalool and limonene are not particularly allergenic; they’re not a big deal in the patch test clinic. The problem comes when we add air to the mix, because they oxidize to hydroperoxides of linalool and limonene. These are quite potent allergens.”
According to the most recent North American Contact Dermatitis Group data, 8.9% of patients undergoing patch testing tested positive to linalool hydroperoxides and 2.6% were positive to limonene hydroperoxides.
Dr. Adler discussed the case of a female massage therapist who presented with refractory hand dermatitis and was on methotrexate and dupilumab at the time of consultation but was still symptomatic. She patch-tested positive to limonene and linalool hydroperoxides as well as multiple essential oils that she had been using with her clients, ranging from sacred frankincense oil to basil oil, and she was advised to massage using only coconut or vegetable oils.
Dr. Brandon L. Adler
Essential oil allergy may also be related to cannabis allergy. According to Dr. Adler, allergic contact dermatitis to cannabis has been rarely reported, but in an analysis of 103 commercial topical cannabinoid preparations that he published with Vincent DeLeo, MD, also with USC, 84% contained a NACDG allergen, frequently essential oils.
More recently, Dr. Adler and colleagues reported the case of a 40-year-old woman who was referred for patch testing for nummular dermatitis that wasn’t responding to treatment. The patient was found to be using topical cannabis and also grew cannabis at home. “She asked to be patch-tested to her homegrown cannabis and had a strong positive patch test to the cannabis, linalool and limonene hydroperoxides, and other essential oils,” Dr. Adler recalled. “We sent her cannabis sample for analysis at a commercial lab and found that it contained limonene and other allergenic terpene chemicals.
“We’re just starting to unravel what this means in terms of our patients and how to manage them, but many are using topical cannabis and topical CBD. I suspect this is a lot less rare than we realize.”
Another recent case from Europe reported allergic contact dermatitis to Cannabis sativa (hemp) seed oil following topical application, with positive patch testing.
Dr. Adler disclosed that he has received research grants from the American Contact Dermatitis Society. He is also an investigator for AbbVie and a consultant for the Skin Research Institute.