Trends in Contact Allergy to Preservatives From 2014 to 2023: Benzisothiazolinone on the Rise

BACKGROUND: Skin sensitising preservatives are commonly used in consumer and industrial products. The widespread use of preservatives has led to recurrent epidemics of contact allergy.

OBJECTIVES: To investigate temporal trends of contact allergy to preservatives from 2014 to 2023.

MATERIALS AND METHODS: Patients consecutively patch tested with preservatives from the European baseline series and the supplementary baseline series at Gentofte hospital from 2014 to 2023 were included.

RESULTS: The study population included 6435 patients. Contact allergy to benzisothiazolinone (BIT) increased significantly from ≤ 0.3% in 2014 to 5.0% in 2023. Painters and machine operators, and assemblers were most often sensitised to BIT, and detergents and paints were the most common exposures to BIT. Contact allergy to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) decreased significantly from 3.3% in 2014 to 2.2% in 2023. Likewise, contact allergy to MI declined significantly from 3.9% in 2014 to 2.5% in 2023. Stable trends were found for the overall prevalence of contact allergy to preservatives from 9.0% in 2014 to 10.2% in 2023.

CONCLUSIONS: Regulatory restrictions on the use of MI and MCI/MI in cosmetic products have led to a decrease in contact allergy. However, the rise in contact allergy to BIT underscores the need for ongoing monitoring and preventive measures.