Bacterial contamination and preservation of cosmetics

What is microbial contamination of cosmetics?
A typical personal care product, such as cream or shampoo, contains many ingredients: water, oils, vitamins, proteins, botanical extracts, emulsifier, etc. Presence of water in cosmetics makes it very attractive for different microorganisms – bacteria and fungi. Their entry and growth in personal care products is called microbial contamination. It can occur during the manufacturing process or during the use by consumers (3). Contamination has an adverse effect on the quality of cosmetic products that may become hazardous for health.

Is your cosmetic product contaminated?
Here are a few signs of contamination:
1. Change of color
2. Change of odor
3 .Change of consistence or texture
4. Appearance of mold – usually looks like grains of various color on the surface of a cosmetic product.

Spoiled cream
Change of color - an obvious sign of spolilage: new cream (left) and the same cream 9 months later (right)

IMPORTANT: Often there are no visible signs of contamination that makes it difficult to recognize without laboratory tests (3).

Possible consequences of contaminated cosmetics:
1. Contact dermatitis (skin condition characterized by itching, redness, cracks, dryness and pain in response to different substances) (9)
2. Appearance of rash or pimples
3. Seborrheic dermatitis (inflammatory skin disorder characterized by flaky, itchy and red skin)
4. Sepsis (dangerous and even life-threatening disease that originates from the whole-body reaction to the infection). People with weak immune system can develop this illness if the cosmetics was contaminated with pathogenic bacteria Pseudomonas aeruginosa or Staphylococcus aureus.

Some facts about contamination:

  • 24 cosmetic products were recalled in the EU due to bacterial contamination during the manufacturing process in 2005-2008 (4).
  • Both small local and big international cosmetic companies have problems with contamination (4)


Preservation of cosmetic products
To avoid contamination preservatives have to be added to the formulation. Preservative is an ingredient or a mix of ingredients used to prevent growth of bacteria and fungi in a cosmetic product.
The ideal preservative is...
- active against all microorganisms
- efficient at low concentration
- colorless and odorless
- soluble in water
- safe to use
- inexpensive
Unfortunately, such preservative has not yet been found (6).

The EU cosmetic regulation lists 59 cosmetic preservatives and their maximum allowed concentrations (5).
There are 5 groups of preservatives mainly used in personal care products (6):
1. Phenolic (parabens, phenoxyethanol, benzyl alcohol). Parabens are the most popular preservatives used in more than a third of cosmetics (7).
2. Formaldehyde and formaldehyde-releasing preservatives (imidazolidinyl urea, diazolidinyl urea, etc.) (more about formaldehyde-releasing preservatives is here)
3. Halogenated (triclosan, chlorphenesin, methylchloroisothiazolinone and methylisothiazolinone (MCI/MI))
4. Non halogen isothiaxolinones (methylisothiazolinone (MI), benzisothiazolinone (BI))
5. Organic acids (benzoic acid, sorbic acid, formic acid)
Cosmetic companies often use a combination of several preservatives to increase their effectiveness against contamination.
The importance of preservatives in cosmetic formulas is unquestionable. However, these ingredients might cause allergic contact dermatitis. Isothiazolinones (for example, MCI/MI), formaldehyde and formaldehyde-releasers are the most allergenic preservatives. In addition, the safety of some traditional cosmetic preservatives is now being questioned. For example, parabens have been found in breast cancer tumors(1). Even though the role of parabens in cancer has not yet been proven, these findings are not to be neglected by both cosmetic manufacturers and consumers (more about parabens here).

Cosmetic product without preservatives?
Water is a primary factor for microorganisms' growth. Therefore, products that do not contain water are usually self-preserving (lip balm, body butter, body oil). Nevertheless, it is important to keep these products away from water or highly humid environment, such as your bathroom. Perfumes and some deodorants-sprays also do not need preservatives due to high concentration of alcohol. In all other cosmetic products use of preservatives or alternative antimicrobial agents is a must!

Additional factors for successful preservation of cosmetics
Apart from preservatives, few other factors will help to prevent growth of microorganisms in a cosmetic product (8):
1. Good manufacturing practices (GMP)
Good manufacturing practices (GMP) are guidelines for manufacturing, testing and quality control of food, cosmetics and pharmaceuticals. The manufacturer must follow these guidelines to make sure that its products are safe for consumers. To reduce the risk of bacterial contamination the producer has to perform microbial testing of raw materials, disinfect the equipment and prepare cosmetics under strictly aseptic conditions (8).
2. Appropriate packaging
An efficient dispersing mechanism is another important factor for preventing in-use contamination of cosmetics. Remember that a traditional wide neck jar is the worst packaging form in terms of preservation  (8). Producers using airless pumps can afford to add less preservatives in their cosmetic product since in-use contamination is minimized. The airless pump is a packaging with a special spring mechanism that does not allow air to get in the tube. In addition, the tiny nozzle minimizes the contact of the cream with your hands.

wide-neck cosmetic jar, airless pump, cosmetic packaging

Different packaging forms for cosmetic products

3. Multifunctional antimicrobial ingredients
Many cosmetic ingredients (e.g. caprylyl glycol, ethylhexylglycerin, some essential oils and botanical extracts) also possess antimicrobial activity. They are not defined as preservatives by the EU cosmetic regulation. Thus, cosmetics containing only those antimicrobial components can be considered ”preservative-free”. However, none of these ingredients is highly efficient alone, therefore, they have to be combined with each other or with traditional preservatives to ensure successful preservation. Another disadvantage is that the natural antimicrobial substances such as essential oils and botanical extracts can cause contact allergy(2). Therefore, if you are subjected to contact dermatitis, a cosmetic product with ”natural preservatives” might not be the best choice for you. In any case, it is important to test the product before using: apply it on the skin at the bend of elbow and leave it overnight. If there is no irritation, apply a small amount on the skin behind the ear and leave it for 24-48 hours. Avoid getting the test-area wet while taking shower.

grapefruit, grapefruit seed extract
Grapefruit seed extract is one of the natural antimicrobials used in cosmetics


This article is based on reviewing multiple studies published in peer-reviewed scientific journals.


  1. Darbre PD, Aljarrah A, Miller WR, Coldham NG, Sauer MJ, et al. (2004) Concentrations of parabens in human breast tumours. J Appl Toxicol. 24: 5–13.
  2. González-Muñoz P., Conde-Salazar L., Vañó-Galván S.(2014) Allergic contact dermatitis caused by cosmetic products. Actas Dermosifiliogr. Nov;105(9):822-32. doi: 10.1016/ Epub 2014 Mar 20.
  3. Lundov M.D., Moesby L., Zachariae C., Johansen J.D. (2009) Contamination versus preservation of cosmetics: a review on legislation, usage, infections, and contact allergy. Contact Dermatitis. 2009 Feb;60(2):70-8. doi: 10.1111/j.1600-0536.2008.01501.x.
  4. Lundov & Zachariae (2008) Recalls of microbiologically contaminated cosmetics in EU from 2005 to May 2008. International Journal of Cosmetic Science, 30, 471-474.
  5. Regulation (EC) No 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products (Text with EEA relevance), Annex 5. Available here.
  6. Roden K. (2010) Preservatives in personal care products. Microbiology Australia. November, 195-197.
  7. Steinberg D.C (2006) 2005 preservative use: frequency report and registration. Cosmet. Toil., 121, 65-69.
  8. Varvaresou A., Papageorgiou S., Tsirivas E., Protopapa E., Kintziou H., Kefala V., Demetzosà C. (2009) Self-preserving cosmetics. International Journal of Cosmetic science. 31, 163-175.
  9. Wolf R., Orion E., Ruocco E., Baroni A, Ruocco V. (2013) Contact dermatitis: Facts and controversies. Clinics in Dermatology, 31, 467–478.


Drosofila's picture

hi! what if I keep my self-made cream in the fridge for, let's say, a week? do I need preservatives?

Natalia's picture

Adding a preservative is necessary for any cosmetic product except water-free (lip balm) or alcohol-containing cosmetics (deodorant-spray). A typical face cream contains 60-70% of water and it is a perfect environment for bacteria. If you do not add preservatives bacteria will start multiply shortly after you prepared the emulsion. Keeping the emulsion in the fridge will slow down the bacterial growth, but it is still very risky. Besides, in many cases you will not be able to recognize contamination. However, you do not have to add preservatives to the products that you are going to fully use right away – for example, face mask, hair mask, body scrub.

Good article - one add.  Grapefruit seed extract is a probem for 2 reasons

1) It's not natural.  The material  as its most commone commerical source Citricidal is a chemically modified extract of grapefruit seed.

2) The material typically includes synthetic biocides - reportedly Triclosan, Parabens and most frequently quaternary ammonium disinfectant (see report from USDA - Identification of Benzethonium Chloride in Commercial Grapefruit Seed Extracts

Natalia's picture

Hi Phil! Thanks for your input!