Allergy to preservatives

Preservatives are chemicals added to products to limit the growth of micro-organisms. Preservatives are added to many types of products, for example, cosmetics, cleaning agents, paper products, industrial oils and paint.

Preservatives are biologically active substances and, therefore, are capable of causing allergic reactions. The chemicals that are the best preservatives are generally also the ones that are the most allergenic. In contrast, the chemicals that are less allergenic are also less effective as preservatives. These preservatives are therefore often used in combination with other, more effective, preservatives.
Some fragrances can be used as preservatives, for example, farnesol and geraniol.

The frequency of allergy to preservatives varies from preservative to preservative. This is being studied across Europe, see below.
 

This is based on tests of more than 50,000 patients with eczema in Europe. It is particularly interesting that since the mid-1990s there has been a dramatic increase in allergies to the preservative methyldibromo glutaronitrile. This is due to an increasing use of the chemical in over-high concentrations. As a result, the EU Commission prohibited the use of methyldibromo glutaronitrile in so-called stay-on cosmetics, for example, moisturizing lotions, which are in contact with the skin for prolonged periods. The ban came into effect in 2005. In February 2007, the Commission made a further move to ban the preservative in wash-off cosmetics, such as liquid soap and hair shampoo. There was a transition period of 15 months where the sale of wash-off products containing the preservative could continue.  

Kathon, another preservative, is also a frequent cause of allergy. Kathon is a combination of methylchloroisothiazolinone and methylisothiazolinone (MI/MCI). Kathon is highly allergenic and although it is used in only very small amounts, it can still cause a large number of allergies.

Scientific publications

Wilkinson JD et al. Monitoring levels of preservative sensitivity in Europe. A 10-year overview (1991-2000).
Contact Dermatitis 2002:46:207-210.

Menné T et al. Risk assessment failures of chemicals commonly used in consumer products. Editorial.
Contact Dermatitis 2002:46:189-190