CD20 What is really in K-beauty serums? Fragrance, botanicals and emerging contact allergens

Abstract

Korean beauty (‘K-beauty’) skincare has rapidly expanded in Western markets, popularizing serums and ampoules marketed as gentle and skin supportive. These leave-on formulations, typically applied to the face and layered within extended routines, increase cumulative exposure to ingredients traditionally used in East Asian skincare. Dermatologists may increasingly encounter facial eczema associated with K-beauty products, without a clear culprit identified on standard patch testing. The aims of this study were to quantify the prevalence of contact allergens in K-beauty serums and ampoules available on the UK high street and to assess their relevance to patch testing practice. In January 2026, a cross-sectional ingredient survey was performed on 190 K-beauty serums and ampoules identified from the websites of two national UK high street cosmetic retailers. Ingredient lists were extracted and analysed. Among the 190 products assessed, the mean number of ingredients was 36 (range 4–78). Humectants included glycols and diols (99%) and acrylate polymers (65%). Botanical ingredients appeared in 77.9% of formulations, including derivatives of Centella (43.7%), liquorice (27.4%), citrus (17.9%), turmeric (13.2%), Artemisia (10.5%), rosemary (10.5%) and tea tree (7.4%). Fragrances included limonene (12.1%), linalool (11.1%), fragrance mix II components (6.8%) and fragrance mix I components (5.8%). Preservatives included ethylhexylglycerin (76.3%), hydroxyacetophenone (17.4%) and benzoates (5.8%). Other frequent ingredients were tocopherol and tocopheryl acetate (37.9%), vitamin C derivatives (27.9%), alkyl glucosides (26.8%) and sorbitan esters (17.9%). Several commonly identified ingredients are not included in the BSCA standard series and lack commercially available patch test haptens. K-beauty serums and ampoules expose facial and eyelid skin to established and emerging contact allergens. The evolving ingredient landscape and limited patch test availability complicate identification of causative allergens using standard testing alone. Careful ingredient review, repeat open application testing and testing with patients’ own products are important when assessing facial dermatitis. The development of patch test haptens for relevant emerging allergens would help address this diagnostic gap.