Sodium Benzoate in Skincare: The Preservative, Explained
Sodium benzoate is a hard-working preservative, and a sensible one to see on a label. It does nothing for your skin directly. Its whole job is keeping water-based products clean and stable, and we'd rather your serum had it than not.
What is sodium benzoate?
It's the sodium salt of benzoic acid. In skincare it's a preservative: it helps stop bacteria, yeast and mould growing in products that contain water. That's why you'll find it in so many toners, serums and cleansers.
What does sodium benzoate do for skin?
It preserves the product. A product that contains water can support microbial growth once it's made and opened.
A preservative keeps the formula stable for the period it's meant to be used. The Cosmetic Ingredient Review (CIR) lists the cosmetic uses of benzyl alcohol, benzoic acid and sodium benzoate as preservatives, fragrance components, solvents and pH adjusters.
It isn't a skin benefit. Sodium benzoate doesn't hydrate, exfoliate or brighten. Whether a preservative is present says nothing about how well a product works on skin, only about how well it's protected.
It usually works as part of a system. Many formulas combine more than one preservative so each can be used at a modest level. Other preservatives you may see in that role include chlorphenesin.
Why we use sodium benzoate
Our toners, serums and cleansers are water-based, so they need protecting. Our formulator uses sodium benzoate as part of the preservative system in these products, alongside other preservatives where the formula calls for it.
Our view: preservatives aren't the villain. An unprotected water-based product is the bigger risk to your skin and eyes.
Who is sodium benzoate good for?
Most people use products with sodium benzoate without a problem. A preservative can still be the cause when a product disagrees with someone, so it pays to know the cautions.
The CIR report notes clinical data on nonimmunologic contact urticaria, a brief hive-like or itchy reaction soon after contact. Take extra care with products intended for infants and children.
If you're prone to reactions, patch test any new product first. Our patch testing guide walks through it. If you have a known allergy, are reacting to a product or have a skin condition, speak with a doctor or pharmacist.
How do you use it?
You don't add sodium benzoate to your routine. It's built into the formula at a level chosen for that product, so the directions on the product apply.
A few habits help any water-based product stay in good condition:
- Keep the lid closed when you're not using it.
- Use clean hands or a clean tool.
- Do not add water or other products into the bottle.
- Follow the storage directions on the label.
Adding extra preservative to a product at home does not make it safer, and mixing your own formulas without training is a risk. If you want to make skincare, take formulating advice first.
What does it pair with?
Preservative systems commonly pair one preservative, such as sodium benzoate, with others. Our Antioxidant Gel Cleanser, for example, lists sodium benzoate alongside phenoxyethanol and sodium dehydroacetate.
On vitamin C: Piper (Beverages, 2018) reports low levels of benzene, a known carcinogen, in some beverages containing benzoate salts together with ascorbic or erythorbic acid. It's thought to form during storage, and heat and UV light promote it. That work is about drinks, not skincare, so it doesn't tell you anything about skincare formulas.
What does the research say?
The short version: well reviewed as a preservative, with assessments that cover the ingredient in general. None of them measure the effect of any Dope Skin Co product.
- Final report on the safety assessment of Benzyl Alcohol, Benzoic Acid, and Sodium Benzoate (CIR, Int J Toxicol, 2001): reports few adverse effects in chronic animal studies, mostly negative genotoxicity results, negative carcinogenicity studies, and the skin reactions described above.
- Opinion concerning benzoic acid and sodium benzoate (SCCNFP/0532/01, 2002): the EU committee's view on non-preservative uses at higher concentrations.
- EU Regulation 1223/2009, Annex V (preservatives allowed in cosmetic products): the list of permitted preservatives and their maximum levels. This copy is the version retained in UK law, which mirrors the EU entry.
- Potential Safety Issues Surrounding the Use of Benzoate Preservatives (Piper, Beverages, 2018): a review focused mainly on food and drinks, including the benzene question.
Safety and regulation
Three reference points, and they're different kinds of limit:
- CIR (2001): safe in cosmetics at concentrations up to 5%, with added caution for products intended for infants and children. The panel also said the data were not sufficient to support safety where inhalation exposure is likely.
- EU rules: Annex V of the EU Cosmetics Regulation permits benzoic acid and its sodium salt as a preservative at up to 0.5% in leave-on products, 2.5% in rinse-off products (except oral) and 1.7% in oral products, all expressed as acid.
- EU safety committee (2002): SCCNFP/0532/01 reviewed a request to use benzoic acid and sodium benzoate for non-preservative purposes at higher concentrations. It did not find the submission adequate for a safety evaluation, noting conflicting genotoxicity results for sodium benzoate. That opinion was about those other uses, not the 0.5% leave-on preservative limit.
The EU figures are the tighter ceiling and the more useful guide for finished skincare, so they're the reference used here.
Sodium benzoate in Dope Skin Co products
It's listed in these products:
- Antioxidant Gel Cleanser
- Glow Tonic
- Glow Serum
- Calming Collagen Tonic
- Calming Collagen Serum
- AHA/BHA Exfoliating Tonic
- AHA/BHA Resurfacing Serum
- AHA / BHA Exfoliating Cleanser
We make our products in-house in Sydney. See each product page for the full ingredient list and directions.
Not sure where to start? Take our skincare quiz.
Frequently asked questions
Is sodium benzoate safe in skincare?
The CIR found it safe in cosmetics at concentrations up to 5%, and the EU sets lower limits for finished products. Individual reactions are still possible, so patch test if you're reactive.
Is sodium benzoate a paraben?
No. Parabens are esters of 4-hydroxybenzoic acid. Sodium benzoate is the sodium salt of benzoic acid, a different compound.
Does sodium benzoate cause cancer?
The CIR report summarises genotoxicity results as mostly negative and carcinogenicity studies as negative. The 2002 EU committee opinion noted conflicting genotoxicity results in the data submitted for non-preservative uses. That's a statement about the studies reviewed, not a promise about any one product.
Does sodium benzoate form benzene with vitamin C?
This has been reported in some drinks that contain benzoate and ascorbic acid, and it's thought to be promoted by heat and light. The research is about beverages, not skincare.
Why do products need preservatives?
Products that contain water can support microbial growth. A preservative protects the formula and the person using it.
Related ingredients
Sources
- Final report on the safety assessment of Benzyl Alcohol, Benzoic Acid, and Sodium Benzoate. CIR, Int J Toxicol 2001. Link
- Opinion concerning benzoic acid and sodium benzoate (SCCNFP/0532/01), 2002. Link
- EU Regulation 1223/2009, Annex V. Link
- Piper. Potential Safety Issues Surrounding the Use of Benzoate Preservatives. Beverages 2018. Link
