Contact allergy to isothiazolinones epidemic: current situation.

Since 2009, an increasing number of published cases of allergic contact dermatitis (ACD) from isothiazolinones in Europe was observed, amounting to an epidemic. However, there are few studies that have assessed the current situation after changes in European regulation.To analyse the incidence of isothiazolinone ACD in our area in the last decade.A retrospective study analyzed all patients patch tested in the Allergy Unit in a tertiary Hospital in Spain between January 2010 and June 2019. Positive patch test reactions to methylchloroisothiazolinone (MCI)/ methylisothiazolinone (MI) and or MI alone were collected.A total of 243 patients (9.55%) with positive patch test reactions to MCI/MI and/or MI alone among 2544 consecutively patch tested patients were recorded. An initial increase in the prevalence of MCI/MI allergy was observed, from 4.5% in 2010 reaching a peak in 2015, followed by a significant decrease until July 2019 with 31% prevalence in 2019.As shown in our data, regulatory intervention have resulted in a dramatic decrease in the prevalence of MCI and MI ACD, reaching a pre-epidemic level of 3.1% in 2019. This article is protected by copyright. All rights reserved.