What about Preservatives?

Preservatives are essential cosmetic ingredients designed to protect products from microbial contamination throughout their shelf life. These ingredients are considered "safe" because their effectiveness and safety have been rigorously tested. The key to formulating cosmetics is to balance minimizing microbial contamination with avoiding skin allergies caused by preservatives. Overusing preservatives can lead to allergic reactions.

Some companies market their products as "preservative-free" or claim to use only plant-based preservatives. However, these alternatives often pose more problems for the skin than synthetic preservatives due to their insufficient antimicrobial and antifungal properties. Microbial contamination is a far greater risk than using small amounts of synthetic preservatives.

In our formulations, we use various preservatives to ensure product safety. One of the  favorites is Optiphen Plus™, a blend of phenoxyethanol, sorbic acid, and caprylyl glycol, which is globally approved for safety. I also appreciate vitamin E (tocopheryl acetate) for its dual role as a preservative and an ingredient, particularly in oil-based formulations to prevent rancidity. In the past, I have formulated serums using very small amounts of parabens (methyl-, ethyl-, propyl-, and butyl-parabens) at concentrations of about 0.1%, equivalent to roughly one drop per 100g of the cosmetic.

Choosing the best preservative for  your cosmetic formulation is crucial for ensuring product safety, efficacy, and shelf-life. The first step is understanding the nature of your formulation, including its pH level, water content, and type of ingredients used. Preservatives are typically more effective in certain pH ranges, so knowing your product's pH is essential. Additionally, water-based formulations are more prone to microbial contamination than anhydrous ones, necessitating a broader-spectrum preservative.

Each preservative has its own set of pros and cons regarding efficacy, potential irritancy, and consumer perception, so it’s important to balance these factors against your product's needs and target market.

Another key consideration is regulatory compliance and safety. Different countries have specific regulations governing the use of preservatives in cosmetics, such as the EU Cosmetics Regulation or the US FDA guidelines. Staying informed about these regulations helps avoid legal issues and ensures consumer safety. Additionally, the safety profile of the preservative must be thoroughly evaluated to avoid allergens and irritants, especially for products intended for sensitive skin or specific demographics like children. Conducting a challenge test, which involves deliberately contaminating the product to see how well the preservative works, is an effective way to test its efficacy. Ultimately, the best preservative for your cosmetic formulation will be one that ensures product safety, aligns with regulatory standards, and meets consumer preferences for safety and efficacy.

Common Preservatives and some facts about them:

• 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