Do ‘cinnamon‐sensitive’ patients react to cinnamate UV filters?

Background:  Use of sunscreens has increased dramatically worldwide, and some sunscreen chemicals may be allergens. Ultraviolet (UV) filters are added to various cosmetic products. Cinnamate UV filters are structurally related to cinnamon-related fragrances. Objective:  The purpose of this study was to determine if ‘cinnamon-sensitive’ patients show positive photopatch tests to cinnamate UV filters and, therefore, should avoid these UV filters. Method:  We photopatch tested cinnamon-sensitive patients (n = 18) with cinnamon, cinnamon-related fragrances, Myroxylon pereirae, and two cinnamate UV filters. Results:  No positive photopatch test to cinnamate UV filters was found (95% confidence interval 0–13%). Discussion:  The risk of developing unwanted allergic contact dermatitis because of cinnamate UV filters in cinnamon-sensitive patients seems to be low, but our study population was small. Therefore, we recommend cinnamon-sensitive patients to perform a use test, for example the repeated open application test, before using cosmetic products containing cinnamate UV filters. In addition, physicians and patients should be aware that many sunscreens contain (cinnamon-related) fragrances and could, therefore, elicit allergic contact dermatitis in cinnamon-sensitive patients, independently from other potential sensitizing components of the sunscreen.