What Is Potassium Benzoate?
Potassium benzoate is the potassium salt of benzoic acid, a naturally occurring compound found in foods like cranberries, prunes and cinnamon. Once chemists recognized benzoic acid’s ability to slow the growth of microbes, they created a more water-soluble version by pairing it with potassium. This step made the ingredient easier to incorporate into liquid and cream formulations.
Commercial production starts with benzoic acid that is neutralized with potassium hydroxide. The result is a fine, white, odorless powder that dissolves quickly in water. Because it stays stable across a wide pH range, manufacturers rely on it as a dependable preservative.
Cosmetic brands first adopted potassium benzoate in the mid-1900s when demand grew for products with longer shelf lives. Today you will spot it in facial cleansers, sheet masks, toners, lightweight moisturizers, hair gels and even some natural-positioned formulas where synthetic preservatives are limited.
Potassium Benzoate’s Cosmetic Benefits/Uses
In cosmetics potassium benzoate serves a single but crucial role: it works as a preservative. By curbing the growth of bacteria, yeast and mold, it helps keep products safe and effective for longer. This protection maintains a formula’s texture, color and scent so the product performs the same way from the first use to the last.
Who Can Use Potassium Benzoate
Because potassium benzoate is used at very low levels and stays chemically stable, it is generally suitable for dry, normal, combination and oily skin. Even sensitive skin usually tolerates it well, though anyone with a known benzoate allergy should avoid it due to the risk of irritation.
The ingredient is synthetic or can be sourced from plant-based benzoic acid, so it fits vegan and vegetarian preferences and is not derived from animals.
Current safety assessments show no specific risks for pregnant or breastfeeding women when the ingredient is used topically at standard cosmetic concentrations, yet this is not medical advice. Expectant or nursing users should confirm any skincare routine with their healthcare provider to be safe.
Potassium benzoate does not make skin more prone to sun damage, so there is no added photosensitivity concern. It also plays well with common actives like vitamin C, niacinamide and gentle exfoliating acids.
Potential Side Effects/Adverse Reactions
Side effects from topical potassium benzoate vary from person to person. The points below outline potential issues, but most people will not experience them when the ingredient is formulated and used correctly.
- Mild skin irritation – a transient feeling of burning, stinging or itching, most often on very sensitive skin
- Redness or rash – localized flushing or tiny bumps that resolve after the product is removed
- Allergic contact dermatitis – rare but possible in individuals with a benzoate allergy, leading to swelling or persistent itching
- Eye irritation – watering or stinging if the product accidentally gets into the eyes
If any of these reactions occur stop using the product and consult a healthcare professional for guidance.
Comedogenic Rating
Rating: 0 on the 0-5 scale.
Potassium benzoate is a small water-soluble salt with no oily or waxy components that could clog pores, so it earns a non-comedogenic score. Its job is to preserve a formula, not to create an occlusive film on skin, making it generally safe for people prone to acne or breakouts.
Because it is used at very low concentrations, it is unlikely to build up on skin even with daily use, further supporting its pore-friendly profile.
Summary
Potassium benzoate works primarily as a preservative, inhibiting bacteria yeast and mold so a product stays fresh smells right and keeps its texture over time. It does this by creating an environment where microbes cannot thrive, all while remaining stable across a broad pH range and dissolving readily in water-based formulas.
While not as buzzworthy as parabens or phenoxyethanol, it appears in a steady stream of cleansers toners gels and sheet masks where brands want a simple low-irritation preservative that satisfies vegan criteria.
Current research supports its safety at the low levels used in cosmetics, with only rare reports of irritation or allergy. Still, skin is individual so it is wise to patch test any new product that contains potassium benzoate to make sure it suits you.