Trends in preservative allergy: Benzisothiazolinone emerges from the pack

Contact Dermatitis. 2021 Dec;85(6):637-642. doi: 10.1111/cod.13968. Epub 2021 Sep 20.


Background: Preservatives are used widely in cosmetic, household, and industrial products to prevent microbial growth and spoiling of the products. There has been a recent epidemic of contact allergy to methylisothiazolinone (MI).

Objectives: To establish emerging trends in preservative contact allergy as MI is replaced.

Methods: We performed a retrospective study on consecutively patch-tested patients at our center from January 2011 to December 2019.

Results: A total of 7846 consecutively patch-tested patients were included who were patch tested between January 2011 and December 2019. The prevalence of allergy to MI fell from a peak of 9.39% in 2013 to 1.98% in 2019. MI/methylchloroisothiazolinone (MCI) followed a similar trend, with a peak prevalence of 7.85% in 2014 and falling to 1.39% in 2018. The prevalence of contact allergy to benzisothiazolinone (BIT) has increased steadily increased in 2014 from 0.26% (confidence interval [CI] 0.03-0.93) to 3.42% (CI 2.43-4.66) in 2019.

Conclusions: Our data show a significant increase in the prevalence of contact allergy to BIT over the last 6 years, probably as a consequence of increased use in household products. It is essential to continue to look for emerging trends in contact allergy to enable prompt preventative measures to be taken.

Keywords: allergy; benzisothiazolinone CAS no. 2634-33-5; epidemiology; methylchloroisothiazolinone; methylisothiazolinone; octylisothiazolinone; preservative; sodium metabisulfite.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Cosmetics / adverse effects
  • Dermatitis, Allergic Contact / epidemiology*
  • Dermatitis, Allergic Contact / etiology
  • Dermatitis, Occupational / epidemiology
  • Dermatitis, Occupational / etiology
  • Female
  • Household Products / adverse effects
  • Humans
  • Male
  • Middle Aged
  • Patch Tests
  • Preservatives, Pharmaceutical / adverse effects*
  • Prevalence
  • Retrospective Studies
  • Thiazoles / adverse effects*


  • Cosmetics
  • Preservatives, Pharmaceutical
  • Thiazoles
  • 1,2-benzisothiazoline-3-one