Allergic contact dermatitis from a natural deodorant: A report of 4 cases associated with lichen acid mix allergy

Background: Botanical ingredients used in personal care products are a significant and underreported cause of allergic contact dermatitis. Objective: To evaluate allergic contact dermatitis from a widely-used botanical deodorant. Methods: We conducted patch testing in four patients who were using the botanical deodorant and were referred to the contact dermatitis clinic; three patients had axillary dermatitis and one had dermatitis of the external ear. Results: All four patients had positive patch test reactions to lichen acid mix and D-usnic acid. Of the three patients who were patch tested to the botanical deodorant, all had positive reactions. Limitations: We did not test to the specific lichen used in the natural deodorant but rather used our own lichen acid mix and d-usnic acid in addition to testing to the actual product. One of the patients declined to be tested with the natural deodorant, but did test positive to the lichen acid mix and d-usnic acid. Conclusion: Personal care products such as deodorants may represent a new route of exposure to lichen extract, a known allergen.