The Safety of Preservatives used in Private Label Skincare
Updated: Sep 12
Preservatives are essential ingredients in water-based skincare products. Without them, bacteria, yeasts, and molds can proliferate during manufacture, storage, or consumer use, leading to product spoilage and potential skin or eye infections. “Preservative-free” claims for aqueous formulas often rely on packaging (airless pumps, single-use), anhydrous bases, or high levels of multifunctional ingredients rather than the complete absence of antimicrobial protection. Regulatory bodies such as the EU Scientific Committee on Consumer Safety (SCCS) and the U.S. Cosmetic Ingredient Review (CIR) evaluate preservatives for safety at specific maximum concentrations. Most approved preservatives pose low systemic risk when used as directed; the primary concerns are local irritation and allergic contact dermatitis in susceptible individuals.
Major Classes of Preservatives
Formaldehyde-releasing preservatives (DMDM hydantoin, imidazolidinyl urea, diazolidinyl urea, quaternium-15, bronopol) slowly liberate small amounts of formaldehyde to control microbes. Formaldehyde itself is a known sensitizer and classified as a carcinogen at high occupational exposures. In cosmetics the released amounts are tightly limited, yet these ingredients still show sensitization rates of roughly 2–3% in dermatology clinic populations. They are restricted or require labeling in many regions and are generally best avoided by people with known formaldehyde allergy or highly reactive skin.
Isothiazolinones (methylisothiazolinone/MI, methylchloroisothiazolinone/MCI, and the MCI/MI combination formerly known as Kathon CG) are highly effective at very low concentrations. Their potency, however, comes with a higher risk of allergic contact dermatitis. Sensitization rates have reached 2–6% or higher in some patch-test series, prompting the EU to ban MI and MCI/MI in most leave-on products and to restrict rinse-off concentrations. They remain a leading cause of preservative-related contact allergy and are particularly problematic for sensitive or previously sensitized skin.
Parabens (methylparaben, ethylparaben, propylparaben, butylparaben and related esters) have been used for decades. They are effective against bacteria and fungi at low concentrations and remain among the most thoroughly studied cosmetic ingredients. Extensive safety data show very low rates of sensitization (typically 0.5–1.7% in patch-test populations). Shorter-chain parabens (methyl and ethyl) are especially well tolerated. Regulatory restrictions apply mainly to longer-chain variants in certain leave-on products or high-concentration uses in some jurisdictions, but the short-chain forms continue to be regarded as safe within permitted limits. Claims linking cosmetic parabens to endocrine disruption or cancer at typical exposure levels have not been substantiated by major reviews; margins of safety remain adequate for normal use. The shorter chain parabens are still an option but we decided to use newer preservatives in our products.
Newer and Safer Preservative Classes
Organic acids and their salts (benzoic acid/sodium benzoate, sorbic acid/potassium sorbate, dehydroacetic acid) function best at acidic pH. They are widely used in “gentle” or natural-leaning formulas and exhibit very low allergenicity (often <0.2–0.5%). Safety margins are favorable, and irritation potential is generally minimal when concentrations stay within regulatory limits. Their main limitation is reduced efficacy at neutral or higher pH, so formulators often combine them with other agents.
Alcohols and related compounds include phenoxyethanol, benzyl alcohol, and certain multifunctional glycols (caprylyl glycol, ethylhexylglycerin, 1,2-hexandiol). These disrupt microbial membranes. Benzyl alcohol can occasionally sensitize but is usually well tolerated at permitted levels. Multifunctional glycols often act as boosters rather than primary preservatives and tend to have low irritation profiles. Phenoxyethanol is discussed in more detail below.
Irritation Potential for Sensitive Skin
Irritation and sensitization are distinct: irritation is a non-immune response (stinging, redness), while sensitization involves adaptive immunity and can produce allergic contact dermatitis on subsequent exposure. For sensitive, atopic, or barrier-compromised skin the ranking of concern is relatively consistent across clinical data:
Highest risk: isothiazolinones and formaldehyde releasers. These account for a disproportionate share of positive patch tests and clinical reactions and thus we do not recommended them nor use them in our products.
Moderate risk: longer-chain parabens or certain older agents such as IPBC when used at higher levels. Again we do not recommend their use or use them in our products.
Lowest risk: phenoxyethanol, sodium benzoate, potassium sorbate, and many multifunctional glycols. Patch-test positivity for phenoxyethanol is typically under 0.5%, and organic-acid salts are among the least reactive. This group are the ones we recommend and use in our products.
Even low-risk preservatives can sting or mildly irritate broken or inflamed skin. Product vehicle, concentration, leave-on versus rinse-off format, and simultaneous exposure to fragrances or other actives all influence real-world tolerance. Patch testing remains the gold standard for individuals with recurrent unexplained dermatitis.
Phenoxyethanol: Safety Profile in Detail
In order to dispel an ever increasing negative attitude towards phenoxyethanol by certain unqualified key board warriors phenoxyethanol is one of the most widely used modern preservatives. Phenoxyethanol is a preservative which is synthesised from ethylene oxide and phenols, which are both found in nature including in green tea, however contrary to popular belief, phenoxyethanol itself is not found naturally in green tea. Sensitization rates are low. Human patch-test data and animal maximization tests show phenoxyethanol is a rare allergen. Clinical studies and dermatology reviews describe it as one of the best-tolerated preservatives available and thus why we chose to it in many of our products. Mild irritation can occur in highly sensitive individuals or on compromised skin, but primary or cumulative irritation is uncommon at cosmetic concentrations. It is not classified as a skin sensitizer by the European Chemicals Agency under normal use conditions.
It offers broad activity against Gram-positive and Gram-negative bacteria and yeasts, with relatively weak effects on the resident skin microbiome which is an important consideration. Maximum permitted concentration in the EU and many other regions is 1%. We use a lot less than 1% in our products (combined with preservative boosters) so exposure is very small. The SCCS concluded in its 2016 opinion that phenoxyethanol is safe for all consumers, including children of all ages, at concentrations up to 1%. Systemic toxicity (including reproductive and developmental endpoints) appears only at exposures orders of magnitude higher—approximately 200-fold—than those resulting from cosmetic use. Genotoxicity and carcinogenicity concerns are not supported at relevant doses. The CIR Expert Panel has repeatedly affirmed it is safe as currently used.
Occasional consumer concerns about phenoxyethanol often stem from high-dose animal data or confusion with unrelated ethylene glycol compounds. At the levels used in finished products, absorption and systemic exposure remain well below thresholds of toxicological concern. It is effective across a useful pH range, compatible with many formulation types, and frequently paired with organic acids or glycols to broaden spectrum while keeping individual concentrations modest. As mentioned above we use phenoxyethanol in a number of our formulations for safe and effective preservation.
Natural and Non Traditional Preservatives
Benzyl Alcohol is found naturally in many plants, fruits, teas, and essential oils like jasmine, ylang-ylang, and hyacinth. Most commercial-grade benzyl alcohol used in cosmetics, skin care, and personal care products is chemically synthesized for cost and scale, though it remains chemically identical to the version found in nature so is considered a nature identical preservative. We use benzyl alcohol in a number of our products including those in our natural range.
Benzoic acid also occurs naturally in small amounts in various plants (like cranberries, plums, apples, and cinnamon) and is formed during some dairy fermentation processes. It too is also synthesised as a sodium salt (sodium benzoate) with its base being nature identical. We use sodium benzoate in most of our products as a safe and effective natural leaning preservative.
Hydroxyacetophenone, do not let the chemical name scare you, it occurs naturally in certain plants, such as cloudberries and the needles of the Norwegian spruce, as well as Artemisia species. Again it is typically synthesized at scale for commercial use yet is chemically identical to its natural sources and is thus considered nature identical. It has a very low overall incidence of skin irritation and is considered a rare cause of allergic contact. It also acts as an antioxidant and an effective preservative booster. There is also some newer research suggesting it has soothing anti-irritant properties as well as being a tyrosinase inhibitor so a true multifunctional ingredient. We have some new products in the pipeline undergoing testing using this preservative.
1,2-Hexandiol is a synthetic, multi-functional cosmetic ingredient that acts as a moisture-binding humectant, a solvent and a mild broad-spectrum non traditional preservative or preservative booster. Clinical tests show it has an ultra-low irritation rate and a comedogenic rating of 0, making it safe for sensitive skin and non-clogging for acne-prone skin. Although it is not a nature identical compound due to its ultra low irritant profile it is becoming an increasingly popular substitute for traditional preservatives and often paired with multifunctional glycols as a self preservation system. Interestingly it is not classified as a preservative under EU rules which is why some products containing it are marketed as "preservative-free" which is in our view being misleading. Due to the demand for more non traditional preservatives we will be releasing more products with this self preservation system in the near future once testing is complete.
Practical Considerations
Many newer preservatives weather natural or synthetic are safe whereas microbial contamination with ineffective or no preservatives is not safe. Choosing preservatives that are well-characterized, safe and have a low-allergic potential is a reasonable approach even for sensitive skin. Regulatory limits, good manufacturing practice, and appropriate packaging together keep the risk–benefit balance strongly in favor of properly preserved skincare for the vast majority of consumers. The route of synthesis or source of a preservative tells you nothing about its safety, which is assessed on the compound itself. Origin is a poor guide to whether an ingredient is appropriate or not.
In summary, if you take an evidence based approach that is backed by real data and not the advice of some unqualified key board worrier you will see that modern cosmetic preservation offers low risk well tolerated options that are safe and effective and the ones we chose to use in our products.
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