Allergic contact dermatitis to edible essential oils: A case report

Essential oils are becoming increasingly popular mainly for their fragrance and their perceived homeopathic benefits. They are derived from a highly variable range of botanicals, many of which contain common allergens such as cinnamic aldehyde, limonene or linalool.1, 2 We report an unusual case of allergic contact dermatitis (ACD) following the ingestion of edible essential oils [doTERRA drops (UT, USA)] in a 58-year-old female presenting to the contact dermatitis clinic. She reported a 2-year history of stomatitis with oral ulcers with minimal cheilitis aggravated by various foods including tomatoes (Figure 1). Other relevant medical history includes recurrent hand dermatitis. The patient was patch tested to the Australian Baseline Series, cosmetics common, fragrance common, cheilitis common, toothpaste and bakery series. Additionally the patient was tested to selected allergens from the essential oils series as well as the patient's own products including her doTERRA essential oils ‘as is’. Allergens were obtained from Chemotechnique Diagnostics (Vellinge, Sweden). The allergens were fixed to the skin with AllergEAZE test chambers (SmartPractice, Calgary, Canada) and occluded for 48 h. Readings were performed according to the International Contact Dermatitis Research Group guidelines on Days 2 and 4. Patch test reactions are summarised in Table 1. Positive allergens were contained in almost all ingredients of the patient's essential oil products as shown in Table 2. She also showed positive reactions to lemongrass oil and lavender, likely caused by reactions to limonene and linalool which are contained in them. The patient was advised to avoid all essential oils, fragrance products and products containing cinnamon, spearmint, citrus, lavender and lemongrass. She reported significant improvements in her stomatitis after reducing the use of oral essential oils when reviewed 1 year later. This is a rare case of intraoral ACD caused by fragrance and spice allergens found in edible essential oils. Similar cases have been reported for products containing cinnamon, spearmint oil, anise oil and L-carvone contained in toothpastes or denture cream.5-7 The Information Network of Departments of Dermatology database from 2010 to 2019 found 908 (8.3%) of the 117 279 patients returned at least one positive result to essential oils.8 Concomitant sensitisation to other fragrances and/or essential oils is also common due to the overlap of allergens, making patients vulnerable to becoming polyreactors.8, 9 ACD to essential oils frequently presents as eczematous and vesicobullous lesions in areas of contact.10 A French study investigating ACD to essential oils also reported oral mucosal damage in one of their patients, but they did not have direct oral essential oil intake.10 There were no other reports of stomatitis secondary to direct essential oil use. In conclusion, we report a rare case of allergic contact stomatitis caused by essential oils in a polyreactor to multiple fragrances and spices. Careful consideration of all foodstuffs and fragrant products needs to be taken when investigating the cause of recurrent stomatitis. A formal written consent has been obtained from the patient regarding the use of a photograph which may show them in a recognisable fashion in this publication. Sangho Lee: Writing – original draft; data curation; visualization. Kajal Patel: Conceptualization; data curation; supervision; writing – review and editing. Bruce Tate: Supervision; conceptualization; writing – review and editing; validation. The authors declare no conflicts of interest.