One of the most persistent challenges in cosmetic formulation is preservation. Few topics generate as much confusion and debate, especially on social media, where discussions often polarise into two opposing camps. On one side, professional formulators emphasise the necessity of preservatives. On the other, a growing movement promotes “natural” products, often without a clear understanding of chemistry or microbiology.
The question is not whether a product sounds appealing or feels luxurious. The real question is much simpler and far more important: is it safe to use?
A beautifully textured handmade cream has no value if it compromises skin health.
why preservatives are essentialPreservatives are not optional additives. They are a fundamental safety requirement in cosmetic products. Their role is to prevent the growth of microorganisms such as bacteria, yeast and mould and to keep products safe throughout their intended shelf life.
Cosmetic preservatives work by creating conditions that inhibit microbial growth. Depending on the system used, they may interfere with microbial cell membranes, enzyme activity or metabolic processes, preventing microorganisms from multiplying. Without preservation, a cosmetic product becomes a suitable growth medium, particularly when water is present.
Microbial contamination is not a theoretical risk. An infected product can cause a wide range of skin problems, from irritation and dermatitis to more serious infections, especially when applied repeatedly or on compromised skin.
when preservation is requiredAny product that contains water requires preservation. This includes emulsions, lotions, creams, serums, as well as products made with hydrosols, floral waters, aloe vera, glycerine or other water-based ingredients.
Preservation is also necessary for products that may not contain water initially but are exposed to water during use. Scrubs are a classic example. Although they are often formulated with oils, butters, sugar or salt, they are typically used in humid environments and handled with wet hands.
This repeated exposure introduces water and microorganisms into the product, creating ideal conditions for microbial growth.
a common mistake with scrubsA frequent misconception is that oil-based scrubs can be protected with oil-soluble preservatives. In reality, this approach is ineffective.
An oil-soluble preservative remains confined to the oil phase. When water is introduced through wet hands or bathroom humidity, microorganisms can grow in the water droplets that form within the product. The preservative cannot reach or protect these areas.
For this reason, scrubs that come into contact with water require a water-soluble preservative, even if the formulation is primarily oil-based. In such cases, the preservative must be properly incorporated, often with the help of an emulsifier, to ensure adequate distribution and protection.
preservatives vs antioxidantsAnother frequent source of confusion is the role of antioxidants.
Ingredients such as Vitamin E (tocopherol), rosemary extract or grapefruit extract are antioxidants, not preservatives. Their function is to slow down the oxidation of oils and butters, helping prevent rancidity and off-odours.
They do not offer any protection against bacteria, yeast or mould. An antioxidant can improve the stability of the lipid phase, but it does not make a product microbiologically safe.
Antioxidants and preservatives serve different purposes and are not interchangeable.
the refrigerator mythStoring cosmetic products in the refrigerator does not replace proper preservation.
Low temperatures may slow microbial growth, but they do not stop it. A product without preservatives stored in the fridge behaves much like food: it has a very limited lifespan, often just a few days.
If you would hesitate to consume food that has been sitting in the refrigerator for over a week, the same logic applies to cosmetic products. Applying an unpreserved product to the skin does not make it safer than ingesting it.
a matter of responsibilityUsing preservatives is not about compromising ideals or abandoning “natural” concepts. It is about understanding that cosmetics are products applied repeatedly to the skin and must meet basic safety standards.
Preservation is part of responsible formulation. It protects both the product and the person using it.
looking aheadThis article is only the starting point. Preservation is not a single ingredient choice but a system that depends on formulation design, pH, packaging and usage conditions.
In the next article, we will look more closely at how preservative systems work, why no preservative is universally suitable for all formulations, and what formulators need to consider when choosing an appropriate preservation strategy.
