Prevalence of methylchloroisothiazolinone and methylisothiazolinone contact allergy in facial dermatitis: a single centre I rish study

Background There has been an increase in methylchloroisothiazolinone ( MCI ) and especially methylisothiazolinone ( MI ) contact allergy in recent years. Objectives We examined the prevalence and demography of MCI / MI and MI contact allergy in patients presenting with facial dermatitis. Methods Eighty patients with facial dermatitis were patch tested to the B ritish S ociety for C utaneous A llergy standard series, preservatives and own products between J anuary 2012 and M arch 2014. Results A total of 14 (17.5%) patients had positive reactions to this preservative. Five (6.3%) patients tested positive to MCI / MI (0.02%), four (5%) patients tested positive to MI (0.2%) and five (6.3%) patients tested positive to both preparations. Six (7.5%) of these patients were atopic. All patients were female and the mean age was 53.8 years. Sources of allergen were in cosmetics and skin care products. Conclusions Contact allergies to MCI / MI and MI are commoner than what was reported before and is an emerging cause of facial dermatitis. The detection rate of this allergen was increased by 5% in our cohort since the inclusion of MI (0.2%) in the standard series.