Axillary Contact Dermatitis in an Adult Caused by Hexamidine Diisethionate From Baby Wipes Labelled “Pure Water”

Baby wipes are a common cause of contact dermatitis in children, particularly on the diaper area and face. The allergens most frequently involved are fragrances and preservatives. Before 2017 and the ban on its use in Europe on non-rinse-off cosmetic products, methylisothiazolinone was a preservative frequently responsible for contact allergies to baby wipes [1]. Such reactions are less common in adults. We report a rare case of allergic contact dermatitis in an adult due to hexamidine diisethionate (CAS No. 659-40-5), an uncommon allergen found in baby wipes [2-4]. A 51-year-old man with a history of childhood eczema presented with eczematous lesions in both axillae (Figure 1A), which later spread to the face (Figure S1). Initial history did not identify any relevant exposures. Treatment with a potent topical corticosteroid led to marked improvement, allowing patch testing to be performed. Patch tests were carried out using the European baseline series, the cosmetic series, and the patient's personal products (Chemotechnique Diagnostics), according to European Society of Contact Dermatitis (ESCD) guidelines [5]. The tests were applied using IQ Ultimate chambers and read on days 2 and 3, following ICDRG criteria. Personal products such as shampoo, soap and deodorant were tested and found to be negative. Positive reactions to potassium dichromate and Compositae mix, both considered irrelevant were observed. A second, more detailed, history revealed that the patient had recently changed to a new brand of baby wipes, which he used on his axillae and face. These wipes, labelled “Pure Water,” listed only two ingredients: water and hexamidine diisethionate (Figure S2A,B). The baby wipes were intended to be used without rinsing. The concentration of hexamidine in the wipes was 0.1%. A Repeated Open Application Test (ROAT) using the wipes of the patient was positive on day 3 (Figure 1B), confirming allergic contact dermatitis (ACD) to hexamidine diisethionate [5]. The patient recalled possible prior exposure to hexamidine during treatment of a panaritium. No recurrence occurred after discontinuing the wipes. While baby wipes are a well-known cause of contact dermatitis in infants, this case of axillary and face involvement in an adult is unusual. To our knowledge, no previous cases have reported baby wipes containing hexamidine diisethionate as the cause of ACD. The diagnosis of ACD was based on the delayed positivity of the ROAT test, which is in favour of contact eczema, and on the low concentration of hexamidine in the wipes, which minimises the risk of irritation. However, irritant dermatitis cannot be formally ruled out. Interestingly, hexamidine was included in our cosmetic series used for patch testing but did not elicit a positive response, suggesting either false negativity or insufficient exposure through this method. The ROAT was instrumental in establishing the diagnosis. Hexamidine is a well-known allergen in the context of antiseptic use, particularly for wound care [4, 6, 7]. When hexamidine is used in cosmetics it is for its emollient, preservative and anti-foaming properties. Its presence in products labelled “Pure Water” is misleading for both patients and clinicians. Baby wipes labelled as “Pure Water” can contain hexamidine diisethionate, a potential allergen capable of inducing allergic contact dermatitis in adults [4]. The ROAT can be key for diagnosis when standard patch tests are inconclusive. The authors wish to thank the team of the medical information department for their invaluable statistical assistance. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Figure S1: S eczema on the patient's face. Figure S2: A and B Baby wipes used by the patient. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.