Article by: Perry Romanowski

On a number of occasions we get asked questions about formulating cosmetics. 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. cosmetic raw materials

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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Formulating Natural Cosmetics

16 comments

  1. Pingback:The Main 8 || Preservatives – Lens of Beauty

  2. Meg

    Hi Perry,

    I have my cleansing lotion: water, some mineral oil, isopropyl myristate, as emulsifier I am using sodium hydroxide/stearic acid. I have added benzoic acid and as preservative, but it failed preservative efficacy test. Why is that ? pH is too high for benzoic acid or benzoic acid is too weak here ? I would appreciate your help.

    1. Perry Romanowski

      It failed because Benzoic Acid is not really a good cosmetic preservative. That is the problem with using “natural” preservatives.

      But you can improve your chances by making sure the pH of your system is below 5.0. If the pH is above this level you will not get any preservative effect from benzoic acid. You might also consider adding another preservative like phenoxyethanol.

      1. Meg

        Hi Perry,

        Right, many thanks. When I am using sodium hydroxide/stearic acid as emulsifier my pH is propably more alkaline than acidic ?

        1. Perry Romanowski

          Well, the pH is closer to neutral and not acidic enough for ingredients like benzoic acid to have a preservative effect.

  3. Clarabelle

    Hi. I’ve been making face creams for years and always used borax as the preservative and emulsifier. Someone gave me a big bag of superfine, powdered borax (they used it to clean their sheep wool) & I’ve recently run out. I ordered some more from intralab. It was more crystalline, in small lumps. It worked as normal (I heat it up in the liquid until it dissolves before adding to the oil) making a lotion. However, after a few days it re-crystallizes back out in the cream, ruining the cream. Are there different forms of borax? Is there one specific type I should be using? I make these creams for myself& friends with problem skin & need to make some more. Could you help advise me please?

    1. Perry Romanowski

      Have you ever done a microbial contamination study on your formula? Borax may not be an adequate preservative!
      Without knowing the rest of the ingredients in your formula I wouldn’t be able to answer why the product is recrystallizing. Yes there are different versions of borax. The exact composition depends on how the supplier made it.

  4. Magdalena Glogowska

    Does it mean you wouldn’t recommend tinted containers (amber, blue, green)?

    1. Perry Romanowski

      Tinted containers can help reduce color and fragrance oxidation but they won’t protect from microbial growth.

  5. Malina

    Are there any guidelines as to the amount or % of a natural preservative you should use in your products?

    1. Perry Romanowski

      Well, you have to use enough of a preservative to prevent microbial growth in your formula. It really depends on the type of ingredients you are using and the type of formula. Typically, preservatives make up no more than 0.5% of the formula.

  6. Liset

    Hi Perry, Thanks for all the information. That is really an important topic. I would like to add that phenoxyethanol is not so well seen by the customers in natural cosmetics formulations although it is accepted as a safe cosmetic preservative by cosmetics regulation agencies.

    1. Perry Romanowski

      Yes, it’s a very complicated subject.

  7. MarkBroussard

    Preservation is a very complex issue and those of us formulating in the “Natural” realm face challenges as the choice of preservatives are more limited and the preservative options are not as efficacious. Preservation is not as simple as adding 1% of a preservative to your formulation. You best think of it from the perspective of a “preservation systems” approach:

    (1) Follow strict GMP: Simple things like always wearing gloves when formulating, wiping down all of your equipment and vessels with alcohol immediately before use.

    (2) Make certain your are using a broad spectrum preservative blend that is effective against bacteria, yeast & mold.

    (3) An effective option is to use as a base, organic acid preservative blends that have a long history of use in the food industry (effective against Fungi – yeasts & molds):

    Potassium Sorbate/Sorbic Acid
    Sodium Benzoate/Benzoic Acid
    Dehydroacetic Acid

    Examples are: Gluconolactone/Sodium Benzoate, Dehydroacetic Acid/Benzyl Alcohol, Benzyl Alcohol/Benzoic Acid/Sorbic Acid

    Other newer options include: Sodium Levulinate, Sodium Anisate, Anisic Acid (Parfum), Salicylic Acid (Organic or Aspen Bark Extract), Citric Acid

    (4) Adjust the pH of your final formulation to 5.0 or below. Since the natural acid mantle barrier of the skin is pH 4.7 to 5.1, formulating at pH <4.5 not only enhances your preservation efficacy, it also minimally disrupts the acid mantle barrier.

    (5) Use preservative boosters:

    (a) Chelating Agents: Tetrasodium Glutamate Diacetate (0.2%) + Citric Acid (.02%) is as effective as EDTA in boosting preservative efficacy

    (b) Glycols: 1,3-Propanediol, Glycerin, Caprylyl Glycol: Help reduce bacterial growth by reducing free water activity. Plus, these are good humectants/moisturizers. Since Glycerin has a very sticky feel on the skin, you might consider using 1,3-Propanediol at 5% and Glycine at 2% in your formulations.

    (c) Phenethyl Alcohol – found in many essential oils, it suppresses odor causing bacteria, and smells like Rose.

    (d) Ethylhexylglycerin: A nice emollient that inhibits bacterial growth.

    You will run across much information that natural preservatives include honey, essential oils, Radish Root Extract, Honeysuckle, etc., but these should not be relied upon as preservatives, but ingredients in your formulation, and, at best, preservative boosters. Don't fall into the trap of thinking that adding Radish Root Ferment and Honey is going to preserve your formulation … might as well just throw in some Kimchi

    1. Liesl-René Milne

      Thank you Perry and Mark!
      I’m still studying cosmetics science and this post is very informative!
      If I may ask…considering this post is from 2014 and I still see many companies currently using gluconolactone/sodium benzoate and potassium sorbate etc in their formulas: what would you forecast as the next big thing in green grade/ecocert preservatives, apart from the newer ones listed above in your post?

  8. Yong Rafidah

    Hi Perry..thanks for wrote doen the most important things for beginner cosmetics formulator like me..

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