Prevalence of methylchloroisothiazolinone and methylisothiazolinone contact allergy in facial dermatitis: a single centre Irish 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 British Society for Cutaneous Allergy standard series, preservatives and own products between January 2012 and March 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.