Preservatives-free

Dermatological or ophthalmological products, from their manufacture to their use, are constantly subject to environmental constraints likely to alter their composition (microbiological contamination, oxidation, etc.). Due to high water and organic matter content, they are a breeding ground for bacterial contamination. They are often also used over long periods of time, which often leads to contamination by the user.

So, preservatives are an essential component of ophthalmic and dermatological preparations, in order to control antimicrobial activity in packaging and prevent degradation of the active substance. The most common are parabens, benzoic or sorbic acid salts, benzalkonium chloride, or chlorobutanol.

For several years, the controversy surrounding these components has led to the development of preservative-free formulations (1).

Indeed, many studies highlight their cytotoxic effects, especially when they are used over sustained periods.

Some ingredients for cosmetic manufacturers are sold in combination with preservatives.
Antimicrobial preservatives act on bacteria or microscopic fungi, stopping them from developing (bacteriostatic or fungistatic effect) or killing them (bactericidal or fungicidal effect).

They can work in three ways: by altering enzyme systems in the bacterial cell, by denaturing proteins, or by modifying the production system by denaturing nucleic acids. In this way, they protect products from contamination during manufacture and when being used by the consumer.

Antioxidant preservatives prevent oxidation by capturing free oxygen. The hydroxyls in their molecule contribute to reduction.
Alcohols that are sometimes present have a drying effect, or plant compounds and perfumes that may cause allergies, irritation and eczema are sometimes included in the ingredients.