The Most Used Preservatives in Cosmetics

Products that contain water in their formulation must be properly preserved. Preservatives in Cosmetics are mainly incorporated into products to prevent their deterioration and prolong their commercial life, as well as to protect the consumer from the possibility of infection against a certain pathogenic microorganism. 

Normally every product is exposed to two types of potentially polluting agents during its use, such as the environment and the consumer himself. When microorganisms penetrate a cosmetic and it is insufficiently preserved, they can multiply in large numbers and the preparation may be affected and its properties transformed by microorganisms.

The ways of presenting this deterioration are quite variable:

  • -Fields of mold on the product
  • -Separation of phases of the emulsions.
  • -Loss of viscosity.
  • -Visual image changes of the product.
  • -Radical changes in the aroma of cosmetics.
  • -Fat rancidity.
  • -Appearance of local stains.

The microorganisms that are usually isolated in cosmetic products can be either bacteria or fungi.

Today, more and more “preservative-free” products are being observed. These products include multifunctional substances or additives, which are not incorporated as an antimicrobial principle but which in the formulation software can provide product stability.

Conservation Systems:

 Physical Conservation:

  • Sterilization: due to the influence of heat, it would only be used for single-use cosmetics and disposable packaging.
  • Drying: by eliminating the water, it would be for extemporaneous use, that is, those that we prepare at that time for immediate use.
  • Radiation: UV, gamma rays.

These methods are not suitable for the preservation of a cosmetic product, but they are of great help in the hygiene program.

Chemical Conservation:

This method includes conservation by incorporating chemical agents into the preparation, thereby protecting it from microbial deterioration.

Preservatives are chemical compounds with antimicrobial effect whose mission is to delay or prevent harmful transformations caused by microorganisms in products.

Preservatives, as they are an integral part of the cosmetic, require a detailed study of the properties of the preservative agent in relation to the product to be preserved, the container that is going to contain it and the type of cosmetic that is going to incorporate it.

Preservative systems most used in cosmetics:


  • Substances that prevent oxidation phenomena responsible for altering the characteristics of the cosmetic.
  • Natural: Vitamin E: alpha-tocopherol
  • Synthetics: BHA, BHT, Gallic Acid, Ascorbyl Palmitate and Vit C esters
  • Ascorbic acid, Sodium sulfite, Sodium bisulfite, Sodium metabisulfite.

B: -Antimicrobial and / or antifungal:

  • Preservative mixtures are usually used to complement the antibacterial and antifungal actions.

Preservatives characteristics:

  • –Prevent or limit microbiological contamination and avoid deterioration of the formula
  • -Bacteria proliferate easily between 30 and 37º C
  • -Fungi and yeasts proliferate between 20-25º C.
  • -Gram + bacteria give off an unpleasant smell, cause turbidity in the formulas.
  • -It is therefore recommended to use a broad-spectrum conservation system.

Natural Conservation Agents:

All formulations that contain water must contain preservatives.

There is no preservative-free formulation unless it is pure petroleum jelly.

The concept of self-preservation and natural preservatives is a relatively new idea in the area of ​​cosmetics and personal care products.

An example is tea tree oil and grapefruit seed extract as new. The latter is effective on a broad spectrum of bacteria, molds and viruses.

However, microorganisms can very easily contaminate a product through repeated use by the user, so it is necessary to consider whether only these products would ensure the maintenance of a microorganism-free condition, not only during storage but also during regular use.

Currently some of the traditional preservative systems are being called into question, so new molecules with biocidal activity or molecules that create an unfavorable environment for microorganisms are being sought.

The reason may be due to consumer demand for natural products or because less toxic compounds are being sought for humans.

The alternative preservative should have most of the characteristics of traditional preservatives, but there is currently none that suits all requirements, so it is advisable to combine different molecules so that we would be talking about a “preservative system”.

The main systems:

-Essential oils:

Such as cumin, cinnamon, eucalyptus, lavender, lemon, rose, sandalwood, thyme, tea tree oil etc.

They are not very effective, they are not effective against bacteria, high concentrations are required, they add odor and color, they are unstable, incompatible with many ingredients, they are irritants and allergens. There is a difference between batches, they generate waste.


Such as animic acid, levulic acid, phenylethyl alcohol, carvacrol, thymol, cinnamaldehyde, eugenol etc. They incorporate odor to the product, they can be irritating, allergenic for certain people.

-Glyceryl esters:

Such as glyceryl laurate, glyceryl caprate, and glyceryl caprylate. Their effectiveness depends on the length of the chain, they are not very effective against fungi.


Such as glycerol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and caprylyl glycol. Its effectiveness depends on the length of the chain. They need high amounts to act as a preservative and this can cause comedogenicity in some cases.