We’ve previously written about cosmetic preservatives and for the most part, there are ingredients that are effective for almost any standard condition a cosmetic product will experience.
However, for a variety of reasons standard preservatives are scary to some people. Cosmetic marketing departments have discovered this and have started requesting that cosmetic chemists come up with formulas that are “paraben free,” “formaldehyde free,” or worse, “preservative free.”
They have no idea how difficult this is.
Why use preservatives?
The first thing to consider is why you are using a preservative in the first place. In a perfect world, cosmetic chemists wouldn’t use preservatives because they typically have absolutely no beneficial impact on the performance of the final product. They are an added ingredient which conflicts with the notion of minimalist formulation.
Unfortunately, the real world is populated with microbes, some of which spread dangerous diseases. Gram negative, Gram positive, yeasts, and molds have all been found to grow in various cosmetics. As a formulator, you need to ensure that these things do not grow and that your cosmetics are not dangerous. Not only is it the ethical thing to do, it’s also legally required.
Unless your product packaging is impervious to microbes (e.g. aerosols) and you’ve made the product under aseptic conditions, you need some kind of preservative system.
Why use parabens & formaldehyde donors?
Now that we’ve established that you need preservatives, it’s just a matter of figuring out which to use. By far the most effective, broad spectrum preservatives you can use include
- Formaldehyde donors
- Halogenated compounds
Other preservatives just aren’t as effective against as many possible microbes.
Additionally, these ingredients have been used for many years with tons of safety data supporting their use. Any new or alternative preservative you would use will not have as much supporting safety data. When all these considerations are added together, there is very little reason to use an alternative preservative.
But if your marketing department insists on handcuffing your formulating efforts by limiting your preservative choice, you can consider some alternatives.
Before giving some alternatives, you should be aware of the regulations. Things are much too complicated for this blog post, but here is a quick summary of cosmetic regulations.
In the USA, cosmetics are regulated by the FDA. The regulations are that essentially you can use any preservative you want as long as your product remains safe. There are a couple preservatives that have been banned or strictly regulated including mercury compounds, hexachlorophene, bithionol, and halogenated salicylanilides. But the FDA does require that you provide proof that each batch you ship for sale is adequately preserved. This means you have to do microbial challenge testing and demonstrate that your product is not “…contaminated with microorganisms which may be pathogenic, and the density of non-pathogenic microorganisms is low.”
If you’re going to use an alternative preservative, you must prove that it works!
In the EU they are a bit more restrictive. If a preservative is not listed on their Cosmetic Directive 76/768/EEC, you can’t use it. Of course, if you want to use a non-listed preservative, there is a process for getting your system approved. It’s just complicated and expensive.
Alternative Cosmetic Preservatives
But if you’re still not dissuaded from using an alternative preservative, here is a list of things that can work. For many of these it will take a high level to get them to work so they would be impractical for most cosmetics.
- Benzoic acid
- Boraxitrus seed extracts
- Copper salts
- Fragrance oils
- Japanese Honeysuckle extracts
- Melaleucol (Tea Tree) oil
- Perillic acid
- Salicylic acid
- Silver Chloride
- Sodium Gluconate
- Sorbic acid
- Usnic acid
- Wasabi extract
- Zinc Salts
The most important thing to remember is that your formula MUST be adequately preserved. It’s ok to try out new, alternative preservatives but understand that you are taking a risk. The alternative preservative may not work as well, may break down over time, and may have some unknown health risks.