Antimicrobial/antibacterial

Such ingredients help to restrain the growth of bacteria and other microorganisms in cosmetics, so that the product remains safe and stable in use for longer. This is especially important for water formulas — creams, gels, shampoos, masks, tonics, where microbes multiply more easily. The FDA notes that cosmetic products can become dangerous when contaminated with pathogenic microorganisms, and preservatives are used specifically to prevent the growth of harmful bacteria and mold, that is, to protect both the product itself and the consumer. (fda.gov)

For skin and hair, this function is most often of indirect importance: such components do not so much "cure" the skin as maintain the purity of the formula during storage and after opening the package. Due to this, the product is less likely to change the smell, texture, color or become a source of irritation associated with microbial contamination. In some products, they also help to better preserve the declared properties of assets. At the same time, certain substances from this group can cause undesirable reactions in sensitive skin, so their concentrations and compatibility with the formula are of great importance. The FDA specifically indicates that some preservatives are common cosmetic allergens. (fda.gov)

Typical examples of ingredients with this function are methylparaben and benzyl alcohol. Parabens are widely used as preservatives and are often combined with other substances for broader antimicrobial action against different types of microorganisms. Benzyl alcohol can also be used as a preservative, while simultaneously affecting the safety of the formula. Therefore, the presence of such components in the composition usually does not indicate the "rigidity" of the product, but that the manufacturer cares about its microbiological stability and safety during the shelf life. (fda.gov)