Do hypoallergenic skincare products contain fewer potential contact allergens?

Personal care products (PCPs) commonly cause allergic contact dermatitis (ACD). Skincare companies often market their products as 'hypoallergenic'; however, this term is not regulated by industry standards. To determine whether PCPs marketed as hypoallergenic are truly less likely to precipitate ACD, we conducted a study of ingredients found in 'hypoallergenic PCPs' from two major UK retailers in 2022. Of 208 products meeting the inclusion criteria, 153 (73.6%) contained at least 1 allergen or related chemical from the British Society for Cutaneous Allergy baseline series, 21 (10.1%) had 2 potential allergens and 4 PCPs (1.9%) had 3 allergens. Cetearyl alcohol was the most common -allergen identified in leave-on PCPs and parabens in rinse-off products; fragrance was the most frequent related chemical found in 85 PCPs (40.1%). A high prevalence of common allergens was found in hypoallergenic PCPs, suggesting that dermatologists and consumers should be cautious of product ingredients.

Ideal proportion of the population to be patch tested: How many should we be doing?

BACKGROUND: How many patients should we be patch testing? A previous study suggested that the minimum proportion of a population to be patch tested for allergic contact dermatitis was 1:700 annually. OBJECTIVES: To evaluate if the current minimum rate for patch testing has changed over the 20 years since the previous study in order to maximize the value. METHODS: In cooperation with the British Society for Cutaneous Allergy, a proforma for collation of retrospective data between January 2015 and December 2017 was sent to patch-test centers in the United Kingdom (UK) and the Republic of Ireland (ROI). The number of positive tests was analyzed against the proportion of population tested to see what proportion of the population would yield the greatest number of positive results. RESULTS: Responses from 11 centers showed that the minimum number needed to patch test had increased to 1:550 per head of population per year using the current criteria. CONCLUSIONS: In agreement with previous studies, we should be patch testing more people than we are. We could reduce the threshold for referral of patients we patch test to derive the most benefit from this investigation.

Dicaprylyl maleate--an emerging cosmetic allergen.

Dicaprylyl maleate (DCM) has been reported rarely as a cause of allergic contact dermatitis. The objectives of this study were to identify patients from multiple centres with allergy to DCM in cosmetic products confirmed by patch testing and, in addition, to investigate the effect of testing with aged DCM. This is an international multicentre study of 22 patients with 26 reactions to products containing DCM. Patch testing was carried out to ingredients including DCM obtained from the manufacturer. Further testing was carried out with deliberately aged DCM in a sample of patients. 22 patients had clinical and positive patch test reactions at 4 days to a total of 26 cosmetic products containing DCM. 5 patients did not react to DCM prepared by the manufacturer from concurrent factory stock but did have positive reactions to a deliberately aged batch of DCM. DCM is an emerging cosmetic allergen. Testing with aged material yields a greater number of positive results. Co-operation between cosmetics manufacturers and clinicians is important in the identification of new allergens.