Most countries around the world have a list of preservatives approved for cosmetic use.
In the EU they are listed in Annex V of Regulation EC 1223/2009 of the European Parliament and for the UK in Schedule 34 of the Product Safety and Metrology Statutory Instrument.
The formulator’s rule for using these preservatives has always been “as little as possible but as much as necessary”. Despite the long use and in-depth safety testing of Annex V materials, a significant proportion of consumers have decided they want alternatives in their cosmetic products.
This has led to the introduction of so-called multifunctional ingredients that, besides their prime function, also have preservative activity. Because they are not as efficacious as those in Annex V, ways of boosting their activity are often needed and these are the focus of this article.