Natural Cosmetic Preservative Questions Answered
On a number of occasions we get asked questions about formulating cosmetics and the best cosmetic preservatives. When there are enough questions on a theme we turn it into a blog post. So here you are, some common questions asked about natural preservatives answered. 
What are some examples of preservatives commonly found in “natural” products?
The type of preservative that you normally find in cosmetic products include ingredients with the name “paraben” in them (e.g. methylparaben, propylparaben, or butylparaben), some type of formaldehyde donor molecule (DMDM Hydantoin, Imidazolidinyl Urea or Quaternium-15), or an organic molecule like Methylisothiazolinone. These are all very effective at stopping microbes from growing in your formula and protecting the consumer. Here is a list of the most common cosmetic preservatives.
However, none of these ingredients are acceptable according to the majority of the cosmetic natural and organic standards. It’s worth pointing out that none of these standards are mandated by the government and you could market a natural product using these preservatives. It’s just that some consumers or consumer watchdog groups might call you out on it.
If you want to produce a safe, natural cosmetic products you MUST use a preservative. Now, you may be able to get away without using a preservative if there is no free water in your formula (natural juices are mostly water) but these instances are less common. For the most part whenever you make a cosmetic, natural or not, use a preservative.
The type of preservative formulators use for “natural” cosmetics include some of the following.
Alcohol
Benzoic acid
Boraxitrus seed extracts
Citric Acid
Copper salts
Essential Oils
Phenoxyethanol
Fragrance oils
Glycerin
Hinokitiol
Honey
Japanese Honeysuckle extracts
Lactic Acid
Melaleucol (Tea Tree) oil
Perillic acid
Potassium Sorbate
Salicylic acid
Salt
Silver Chloride
Sodium Gluconate
Sodium benzoate
Sorbic acid
Sugar
Usnic acid
Wasabi extract
Zinc Salts
For professional formulas the most common are Sodium Benzoate, Phenoxyethanol, or Sorbic Acid. However, these don’t work for every application. Figuring out a natural cosmetic preservative is highly dependent on your particular ingredients.
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How long will a product preserved with natural cosmetic preservatives last?
This is really dependent on the level of testing that the company who made the product requires. A large, reputable company insists that their products have a shelf life of at least one year. This should be the standard for everyone but some smaller companies are happy with products that last 6 months. The length of time it lasts also depends on where the consumer stores it and how they use the product.
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How do these preservatives work?
Standard preservatives work in a variety of ways but typically it is by disrupting the cell walls of microbes.
Natural preservatives do this to a lesser extent, but they also help to bind water molecules. For example, honey or sugar are able to bind up water molecules so no microbe is able to use that water to fuel growth. Honey is so effective at keeping water bound to it that it can stay preserved for nearly 1000 years.
Another way that natural preservatives work is by lowering the pH of the formula. Most microbes prefer a pH range of 5 to 7.5 for growth. So if you keep the pH range below 4 you can prevent most microbial growth. However, this isn’t completely effective because there are extremophiles that can thrive at any range of pHs. Fortunately, they are rarely found in cosmetics.
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What types of bacteria are found in cosmetics? Are they dangerous? How long does it take to become sick?
There are a number of types of microbes that can grow in cosmetics and some of them are dangerous.
There is the Staphylococcus Epidermidis bacteria that can be found living on color cosmetics like lipsticks, eyeshadows and eyeliners. This bacteria naturally lives on the skin but some strains can cause infection. This is why you shouldn’t share color cosmetics with another person.
Another bacterial group in your cosmetics is Staphylococcus Warneri which is normally found on the skin. If you are sick and have a compromised immune system this bacteria can cause problems. In extreme cases, this bacteria has been associated with heart valve damage. It’s something you want to avoid.
Then there are bacteria that can cause pneumonia, lower respiratory infections, urinary tract infections and more. There are also yeasts that can cause thrush, and a variety of molds that can cause allergic reactions, cornea infections, and lung damage.
See this post for a longer list of specific bacteria in cosmetics.
The length of time you have to be exposed to a microbe to develop a sickness depends on too many factors to give a simple answer. It could be just a couple of microbes one time and you get sick. Or you could be one of those people who are particularly tolerant of microbes and you never get sick no matter how much exposure you have. Since you can’t know it’s best to avoid exposure whenever possible.
What are some signs a natural cosmetic formula has gone bad?
There are a number of indications that your cosmetic has gone bad. The most obvious one is black or white spots spread throughout the formula. Those are growth colonies.
Another obvious indication is an odor change. If the product doesn’t smell the same as when you first bought it that could be a sign that it’s been contaminated. The formula should be discarded.
Another sign that the product has gone bad is that the color may have changed. If it is not the same color as when you first got it, microbes could be lurking in the formula.
Finally, if the formula is more thin than when you first got it this could be a sign of microbial contamination.
Where is the best place to store natural beauty products?
Since natural beauty products use preservative systems that are not as effective or robust as standard products you may be able to store the product in places that are less conducive to growth.
Most microbes prefer a warm, dark, damp place to thrive. So if you can keep them in a cooler environment they will not grow as quickly. Also, if you can keep the products stored in a place that gets more light this can help inhibit growth of some types of microbes. Of course, some microbes thrive in light conditions so none of these are sure fire solutions. Perhaps the worst place you can keep you cosmetics is in a dark cabinet under your sink. This is fine for most standard products but if you have a natural cosmetic and it uses one of the alternative cosmetic preservatives your best bet is to leave the product on your bathroom countertop away from the warm shower.
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