Contact sensitization to preservatives

The frequency of contact sensitization to preservatives varies greatly, e.g., depending on their respective usage and allergenic potential. In recent years, methylisothiazolinone (MI) has increasingly been used for preservation of cosmetics and body care products. Against this background, we analyzed data of the Information Network of Departments of Dermatology (IVDK) of the years 2009 2013. The German Contact Demiatitis Research Group (DKG) preservative series was patch tested in 38,376 patients. Sensitization to methylisothiazolinone (MI) increased from 1.9% to 7.1% in the study period. In parallel, positive reactions to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) increased from 2.4% to 6.5%, probably in most cases due to cross reactions to MCI in patients primarily sensitized to MI. In contrast, reaction frequencies to all other preservatives tested largely remained constant. To methyldibromo glutaronitrile (MDBGN), 2.9% positive reactions were observed, followed by iodopropynyl butylcarbamte (TPBC) with 1.4%. Sensitization to the other preservatives was noted in 0.2% 0.8% of the patients tested. In spite of their widespread use, sensitization to parabens occurs very rarely; there are only few reactions to paraben mix and, moreover, only about half of these reactions indicate contact sensitization.