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Preservatives and the Microbiome

Preservatives play a crucial role in protecting skincare products from harmful bacteria, fungi, and other microorganisms. Every time you use a skincare product there's a risk of introducing harmful microorganisms into the product especially if your not using airless pump jars. Once in the product these microorganisms can multiply contaminating the product and making it unsafe to use. By including preservatives in skincare formulas, manufacturers ensure that their products are safe from harmful microorganisms.

Your skin is home to trillions of microorganisms such as bacteria and fungi and they form what we call the "skin microbiome." Recent scientific research has shown that the skin microbiome plays a vital role in maintaining skin health and appearance. If the balance is disrupted then skin health suffers resulting in inflammation, aging and a reduced barrier function so it is important to maintain a healthy skin microbiome.

There is a tonne of misinformation on the internet sprouted by unqualified bloggers, influencers and various websites in regards to the dangers and risks of various ingredients used in cosmetics despite scientific evidence proving the contrary and now this same zest to scare monger the public has turned to the use of preservatives used in cosmetics and their effect on the microbiome based on assumptions and opinions but not based on any proof.

Statements such as “preservatives used in cosmetics will decimate your skin microbiome” found on the internet are nothing more than baseless scare mongering usually used to promote their own products using alternative natural preservatives.

Another one “Since the purpose of preservatives is to eliminate microorganisms that may be present in products, it makes sense that they could also eliminate them in your skin's microbiome, including the good ones!”. Makes sense is an assumption not proven fact.

A recent publication in 2021 by Murphy et al.1 states: “An analysis of four in vivo studies that examine the impact of different preservation systems in full formulation, in different products formats, with varying durations of application demonstrated that despite the antimicrobial efficacy of the preservatives in vitro, the skin microbiome is not impacted by preservative containing products in vivo.” This means despite the preservatives having an antimicrobial effect in the product in the jar once applied to the skin the preservative had no effect on the microbiome on the skin.

Many claims on the internet suggest the authors believe that the microbiome is very delicate and easily eradicated. Although we still have much to learn about the skins microbiome but delicate it certainly is not. The microbiome has evolved over thousands of years to flourish on the skin at times under extreme conditions so is not all that delicate as some may believe. It has adapted to various skin care products that our species have used since early civilisations. In addition, microbes have an amazing ability to mutate and resist novel chemicals (natural and synthetic) that they may encounter. Thus, it could be rather naïve on our part to treat the microbiome as a fragile system, susceptible to change due to exposure to cosmetic products. While it is possible that a new chemical may adversely affect one or more of the microbial species in the short term, we could expect over time to see it readjust to a healthier natural state as it mutates and adapts which is what it has been doing for thousands of years.

What negative effects of preservatives in skin care products were found before the microbiome-conscious era of skin biology research?. Did product safety investigations reveal any serious concerns (which in hindsight may be due to microbiome dys-biosis) that caused the recall or discontinuation of typical moisturizing or anti-aging products? The answer is no. Therefore before we even knew of the importance of the skin microbiome cosmetic products containing preservatives had no detrimental effects which further suggests that the risk has been highly inflated for personal gain.

The importance of the skin microbiome is certainly acknowledged and here at PLC we are following the research to ensure our products promote a healthy balance. We also chose to avoid using certain preservatives as in our experience they tend to cause more sensitivity reactions than others however we do not condone the scare mongering going on that are baseless assumptions not based on any research. More research is needed however at this stage it appears that preservatives protect the product inside the jar but once applied to the skin seem to have little effect on the microbiome.

We favour traditional preservatives like phenoxyethanol and benzyl alcohol as they have been proven to be safe and very effective but also introducing innovative multifunctional ingredients that form self preservation systems.


1. B. Murphy, M. Hoptroff, D. Arnold, R. Eccles, and S. Campbell-Lee, In-vivo impact of common cosmetic preservative systems in full formulation on the skin microbiome, PLoS ONE, 16(7): e0254172 (2021);



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