Cosmetic and beauty products are made up of ingredients that are biodegradable, and this means that microbes can easily break them down. This causes a product to become unpleasant and unsafe for consumers with an added antimicrobial. Preservatives are antimicrobial ingredients added to product formulations to maintain the microbiological safety of the products by inhibiting the growth of and reducing the amount of microbial contaminants. We, at Microchem Laboratory, are proponents of cosmetic and personal care manufacturers using preservatives at safe levels to ensure the microbiological quality of their products. Below is a list of the 5 most common types of preservatives used in cosmetics, along with some examples, uses, and pros and cons of each to assist cosmetic and personal care producers in the decision of the most appropriate preservatives for their products.

  • Parabens
    • Examples
      • Germaben II
      • Methylparben
      • Propylparaben
      • Butylparaben
    • Economical
    • Most widely used group of preservatives
    • Effective for fungal protection and some gram positive bacteria
    • Must be combined with others for gram negative protection
    • Allowed for both rinse-off and leave-on products
    • Concerns about estrogenic activity due to study – the study was disputed, but public now perceives them as dangerous and it is difficult to turn that around. It was concluded they were safe for use in cosmetic products at levels up to 25%. Typically parabens are used at levels ranging from 0.01 to 0.3%.
  • Formaldahyde Releasers
    • Examples
      • Germall Plus
      • DMDM Hydantoin
      • Imadozolidinyl Urea
      • Diazolidinyl Urea
    • Effective for bacteria, weak fungal efficacy
    • Releases formaldehyde as needed so maintains low levels
    • The use of formaldehyde-releasing preservatives ensures that the actual level of free formaldehyde in the products is always very low, yet sufficient to ensure microbial inhibition.
  • Isothiazolinones
    • Examples
      • Kathon
    • Broad spectrum effectiveness
    • Best for Rinse–off products
    • Effective over the entire pH range normally encountered in cosmetics
    • Toxicological data has shown them to be non-carcinogenic
    • May cause skin irritation for some consumers
  • Phenoxyethanol
    • Examples
      • Optiphen, Optiphen Plus (contains phenoxyethanol combined with others for broad spectrum protection)
    • Often considered a "milder alternative" to traditional preservatives
    • Not broad spectrum (by itself)– often combined with caprylyl glycol, sorbic acid/potassium sorbate or EDTA to create broad spectrum efficacy.
    • Good bacterial efficacy, best against gram negative bacteria
    • Very stable, not pH dependent
    • Allowed in most areas up to 1%, though found to be non-irritating or sensitizing up to 2.2%
    • Concerns of carcinogenic activity
  • Organic acids
    • Examples
      • Benzoic Acid/Sodium Benzoate
      • Sorbic Acid/Potassium sorbate
      • Levulinic Acid
      • Anisic Acid
    • Higher use levels to be effective leading to higher costs
    • Aqueous base required
    • Effective against most fungi with weak efficacy against bacteria
    • Often combined with other organic acids or diazolidinyl urea (DU) for broad spectrum effectiveness
    • Considered to be “natural alternatives” though they are often made synthetically
    • Precipitate in high water content and become no longer active
    • Require pH 2-6

For more information regarding preservatives used in cosmetics, contact the lab or get a same-day price quote for preservative challenge testing to verify that your preservative is effective in your formulation.