Preservation is the part of cosmetic formulation with the worst public reputation and the strongest technical case. It is also the clearest example of a pattern this publication keeps returning to: a genuine consumer concern, taken up by marketing, converted into a claim, and then used to sell products that address the claim rather than the concern.
Why a preservation system exists
Water is a habitat. A cream, a lotion, a gel or a micellar water contains water, usually contains nutrients in the form of oils, proteins, sugars or botanical material, and is stored at room temperature. It is then opened, exposed to air, touched with fingers, kept in a bathroom, and used over weeks or months.
Without something to prevent it, that product can support bacteria, yeast and mould. The consequences range from spoilage to eye infections. This is not a hypothetical: contaminated cosmetics are a recognised route of infection and are one of the categories that appear in product safety enforcement. The Office for Product Safety and Standards publishes recalls and alerts, and microbiological contamination is a recurring reason.
How a preservation system is chosen
There is no universal preservative. A formulator selects a system against several constraints at once, and the choice is frequently the last thing to be settled because everything else has to be fixed first.
- pH range. Many preservatives only work within a particular pH window, and some are inactivated outside it. A formula at a low pH has different options from one at neutral.
- Solubility. The preservative has to be in the water phase, because that is where organisms live. A preservative that partitions into the oil phase is not protecting the product.
- Interactions. Certain ingredients, including some non ionic surfactants and some polymers, can bind preservatives and reduce their availability.
- Regulatory status. The annexes to the retained cosmetics regulation list permitted preservatives with maximum concentrations and, in some cases, conditions of use and required warnings.
- The pack. An airless pump or a tube reduces exposure. An open jar increases it, which raises the burden on the preservation system.
Proving it works: the challenge test
A preservation system is not accepted because it is theoretically adequate. It is proved by a preservative efficacy test, sometimes called a challenge test, in which the finished product is deliberately inoculated with specified organisms and sampled over a set period to confirm that populations fall at the required rate.
The test is run in the final pack because the pack is part of the system. A product that passes in a tube may not pass in a jar. This is one of the several reasons that pack decisions are formulation decisions, discussed further in packaging decides more than you think.
A formulator will accept a great deal of interference on texture, fragrance, colour, active level and cost. Preservation is where most of them stop. A product that fails challenge testing does not go out, because the failure mode is not disappointment. It is infection, a recall and an enforcement file.
The free from claims, and what they are doing
Free from claims are commercially powerful because they are simple, and they are problematic because they usually imply something they do not say. A claim that a product is free of a named preservative does not tell you what is being used instead, whether the alternative is used at a higher level, or whether the alternative has a better or worse safety record.
The Competition and Markets Authority has been clear in the context of environmental claims that a statement can be misleading through what it implies as well as through what it says, and the same reasoning is applied to safety implications by the advertising codes. A free from claim that suggests the omitted substance is unsafe, where that substance is permitted and has been assessed, is the case most likely to be challenged.
Free from parabens, sulphates and silicones
That the product does not contain substances from those three chemical families. Each of the three describes a group of materials with quite different functions: preservatives, cleansing surfactants and a broad class of emollients and film formers.
Taken purely literally, the statement can be true and verifiable from the ingredient list.
It does not mean the product is safer. It does not mean the omitted substances are unsafe, and several of them are permitted, assessed and used within set limits. It does not mean the replacements are better tolerated, better evidenced or present at lower levels. It does not mean the product is gentler, more natural or better for sensitive skin, none of which follows from the absence of a chemical family.
It also says nothing about what the product does contain, which is the part that determines how it behaves on your skin.
For the strong reading to hold, the brand would have to show that the omitted substances present a risk in cosmetic use at permitted levels, and that its replacements do not. That is a substantiation burden, and it is the reason most free from claims are written as bare statements of absence rather than as statements about safety.
Products that genuinely do not need preservatives
There are real cases, and it is worth naming them because the category is not entirely marketing.
- Anhydrous products. Oils, balms and waxes that contain no water offer nothing for organisms to grow in. They can still go rancid, which is oxidation and a different problem addressed with antioxidants.
- Very low water activity. High concentrations of certain humectants or salts can reduce available water enough to inhibit growth.
- Extreme pH. Some products sit at a pH hostile to most organisms.
- Single use or refrigerated formats. Ampoules and cold chain products shift the problem to the format and the supply chain.
Each of these is a legitimate strategy and each has a cost. Anhydrous products feel different. High humectant systems can be tacky. Single use formats produce a great deal of packaging. There is no free option, only a choice about where the cost lands.
Turning an ingredient class into a villain
Free from claims are cheap to make and expensive to answer. Creating doubt about a widely used ingredient class costs a challenger brand nothing and forces incumbents into a defensive position they cannot win, because reassurance is less shareable than alarm.
Once the doubt is established, an entire product range can be positioned on absence rather than on performance, which is easier to formulate to and much easier to write copy for.
- Challenger brands. Get a point of difference that requires no formulation advantage at all
- Ingredient suppliers of the substitutes. Gain a category shift they did not have to fund
- Retailers. Get a filterable attribute for their websites, which drives navigation and sales
- Publishers and creators. Get durable, high engagement content about what to avoid
A description of a recognisable marketing mechanism. No claim is made about the safety of any specific ingredient here, and none should be read into it.
What a sensible shopper does with all this
Stop treating the absence of a chemical family as information about a product, and start treating the pack and the period after opening as information about how long you have. If you buy an open jar, use clean hands or a spatula. If a product is a water based one with no obvious preservation system named on the list, that is worth a question to the brand rather than a purchase.
If you have a specific ingredient sensitivity, the ingredient list is the tool that helps you, and a dermatologist is the person who can identify what to look for. The British Association of Dermatologists publishes patient information on contact allergy and patch testing, which is a far better route than a free from label.