[Preservative allergy : An enduring issue]

Preservatives in cosmetics are often suspected as contact sensitizers and hence frequently patch tested in dermatitis patients. Exposure in this field has changed over the course of years.

To describe the frequency of contact sensitization to various preservatives.

Retrospective data analysis from the Information Network of Departments of Dermatology (IVDK) for the years 2009-2018.

Frequency of sensitization to methylisothiazolinone (MI) has increased from 2.0% in 2009 to 7.2% in 2013. Since 2014, the rate has been falling again. Increasing the patch test concentration of methyldibromo glutaronitrile (MDBGN) in 2016 has caused a sudden rise in positive patch test reactions from 2.0% to more than 4.5%. Allergic reactions to other preservatives occurred in less than 1% of the patients tested.

Since 2014, the worldwide "epidemic" of sensitization to MI has been subsiding in Central Europe, thanks to corresponding restrictions on use. Since 2008, there is no longer any widespread exposure to MDBGN; the new, higher test concentration elicits many false-positive test reactions and explains the sudden rise in positive patch test reactions since 2016. Despite widespread use, phenoxyethanol, benzoates, benzyl alcohol, parabens and sorbates rarely cause allergic reactions. Therefore, they can be recommended for cosmetics from the epidemiological-allergological point of view.