Sodium Benzoate Preservative Formulating Guidelines & Safety
Sodium Benzoate is an anti-fungal preservative derived from benzoic acid, a compound that occurs naturally in some plants. Sodium benzoate is manufactured for cosmetic use and is most effective in acidic skin and hair formulations. It is used as part of a preservation system rather than as a complete broad-spectrum preservative on its own.
It can also be used to help mask strong fragrances in skincare products and act as a corrosion inhibitor. It is relatively effective against yeast and molds mainly and shouldn't be used on its own.
Let's keep reading to learn more about Sodium Benzoate, safety and usage instructions when utilizing it to extend the shelf life of your beauty products.
Sodium Benzoate Quick Facts
| Sodium Benzoate INCI: |
| Sodium Benzoate |
| COSMOS and ECOCERT Standards: |
| Sodium Benzoate meets COSMOS and ECOCERT standards |
| Sodium Benzoate Ingredients: |
| Benzoic acid, sodium hydroxide |
| Sodium Benzoate Preservation Activity: |
| Sodium benzoate works by releasing benzoic acid, which is absorbed into cells, inhibiting the growth and replication of microorganisms. This activity increases as pH falls. |
| Is Sodium Benzoate Water Soluble? |
| Sodium Benzoate is water-soluble up to 55%. |
| PH Compatibility: |
| Sodium Benzoate can have some activity at a pH of 6 but is most effective at a pH of 3. |
| Recommended Usage Levels: |
| The recommended usage level for Sodium Benzoate is up to .5% in leave on products. |
What is Sodium Benzoate?
Sodium Benzoate is the sodium salt of benzoic acid. It is soluble in water, where it converts to its active form, benzoic acid, in low pH environments.
Benzoic acid is a natural anti-fungal agent that inhibits the growth and replication of microorganisms.
Sodium Benzoate and Food
The use of Sodium Benzoate as a food preservative is regulated by the US Food and Drug Administration (FDA) and other international food regulatory organizations. The FDA has classified it as a GRAS (Generally Recognized as Safe) substance for use in food. It is authorized for use as a preservative in all food categories, including beverages, dairy products, meat and poultry, and baked goods.
Oftentimes you will find sodium benzoate in:
- soft drinks
- fruit juices
- salad dressings
- dairy products
Just because a preservative is GRAS certified doesn't mean you can't have reactions or issues with it.
Sodium Benzoate and Cosmetics
The use of Sodium Benzoate in personal care products & cosmetics is also regulated by international organizations such as COSMOS and ECOCERT.
These organizations have classified it as a safe and effective preservative for use in cosmetics, including skin and hair products. It is approved for use in all cosmetic categories.
How Does Sodium Benzoate Work?
Sodium Benzoate works by releasing benzoic acid, which is absorbed into cells, inhibiting the growth and replication of microorganisms. This activity increases as pH falls.
Sodium Benzoate is not a broad spectrum preservative for cosmetic use and should be used in combination with other preservatives.
Its strongest activity is against fungi, including yeast and molds; its coverage against bacteria is limited.
It is often used in combination with Potassium Sorbate in low-pH products to help control yeast and mold. Both work in similar acidic conditions, but the combination can still leave bacterial-coverage gaps and should not automatically be treated as a complete preservation system for a water-containing product.
| Sodium Benzoate CAN | Sodium Benzoate CANNOT |
|---|---|
| Contribute preservative activity in appropriately acidic formulas | Be assumed to provide complete broad-spectrum preservation by itself |
| Help control fungi and yeast | Make every sodium-benzoate/potassium-sorbate formula automatically broad-spectrum |
| Be part of a broader preservation system | Compensate for poor manufacturing hygiene or missing preservation testing |
| Be used in the aqueous phase according to supplier guidance | Be treated as universally effective regardless of final pH |
Is Sodium Benzoate Natural?
Sodium Benzoate is a man-made compound. It is derived from Benzoic Acid, which can be found in many plants.
Sodium Benzoate Cosmetic Uses
We've learned quite a bit about this skincare preservative, but let's dive a little bit deeper into how to incorporate it into your product formulations.
How to Use Sodium Benzoate Preservative in Product Formulations
Sodium Benzoate contributes more preservation value as the finished formula becomes more acidic. As the Quick Facts explain, activity is greater at pH 3 than at pH 6. A final pH around 5 or below is commonly useful for meaningful activity, but there is no single correct pH for every product. The finished formula, supplier guidance, skin compatibility, and complete preservation system still matter.
When using sodium benzoate, the pH should be lowered only as appropriate for the finished formula and supplier guidance; a lower pH favors its active benzoic acid form.
This preservative is often mixed with other preservatives such as potassium sorbate, but this pairing does not automatically provide complete broad-spectrum protection. The full preservation system must address the formula’s bacterial, yeast, and mold risks. Depending on the formula, a properly designed, pre-blended broad-spectrum system may be a better choice.
It is recommended not to exceed a .5% in leave-on products.
Supplier guidance and applicable limits for the specific product and formula take precedence. The concentration needed depends on the exact material and the complete preservation system; a usage percentage alone does not confirm adequate preservation.
Be sure to test your product pH in the finished formula, after all ingredients are incorporated, to check that it is appropriate for the preservation system.
Sodium benzoate is water-soluble and belongs in the aqueous portion of a formula. Dissolve it in water as appropriate for your supplier’s instructions, then check and adjust the final formula’s pH. Follow the processing guidance for your specific material rather than assuming one temperature suits every formula.
Sodium Benzoate Dangers & Warnings
Sodium Benzoate can be part of a preservation system, but neither sodium benzoate alone nor its combination with potassium sorbate should automatically be assumed to provide complete broad-spectrum protection. The full formula and preservation system need to be evaluated.
There are multiple broad spectrum, natural preservatives that include sodium benzoate as an ingredient like:
- Geogard® 221 (also known as Sharomix 721)
- Dermosoft® 1388 ECO (also known as Plantaserv C)
- Euxyl® K712 (also known as Saliguard® SP)
Compatibility depends on the full formulation. One combination that requires particular care is sodium benzoate with L-ascorbic acid.
Sodium benzoate and L-ascorbic acid: formulation precautions
Benzene formation has been associated particularly with benzoate and ascorbic acid under certain conditions. Sodium benzoate by itself should not be described as creating benzene. For DIY formulations, avoid combining sodium benzoate with L-ascorbic acid unless you have the expertise and testing to evaluate the system.
For DIY Vitamin C Serums or creams containing L-ascorbic acid, choose a suitable preservation system rather than combining it with sodium benzoate without the necessary expertise and testing.
Benzene formation depends on formulation and storage conditions; factors such as heat, light, and trace metal ions can influence the reaction. The conservative DIY approach is to avoid the benzoate and L-ascorbic acid combination rather than assume that controlling one factor makes it safe.
Ordinary citric acid is not the same ingredient as L-ascorbic acid. Do not extend this warning to citric acid simply because it is acidic; compatibility must be considered in the context of the complete formula.
Where to Buy Sodium Benzoate Preservative
Sodium Benzoate - Lotion Crafter
Lotion Crafter offers a wide variety of ingredients for all of your formulating needs. They offer carriers oils, preservatives, exfoliants, anti-aging ingredients, butters and so much more. I order a lot of my supplies from Lotion Crafter. Lotion Crafter offers local & International shipping.
Sodium Benzoate - Wholesale Supplies Plus
Wholesale Supplies Plus offers a wide range of soap making & formulating supplies including bases, additives, carrier oils, fragrance & more. They are based in the US & while they do offer International shipping, they currently do not serve EU member states.
Sodium Benzoate | Formulator Sample Shop
Formulator Sample Shop carries a wide range of formulating and skincare ingredients including carrier oils, butters, preservatives, and more. You are able to purchase the exact quantities that you need, and if there is something you need that you don’t see on their website, just contact them! They do offer International Shipping as well.
Sodium Benzoate Skincare FAQs
We've covered a lot about sodium benzoate but you can find more answers to commonly asked questions in our FAQs:
Is sodium benzoate a broad-spectrum preservative?
No. Sodium benzoate is strongest against fungi and yeast, with limited bacterial coverage. It can contribute to a broader preservation system, but it is not a complete broad-spectrum system by itself.
What pH does sodium benzoate work best at?
Its activity increases as pH falls. A finished pH around 5 or below is commonly useful for meaningful activity, but the right pH depends on the formula, supplier guidance, skin compatibility, and complete preservation system. Check the final formula rather than relying only on the starting water pH.
Can sodium benzoate and potassium sorbate be used together?
They are commonly paired because they work in similar acidic conditions. Both lean toward fungal and yeast control, so the combination can still leave bacterial-coverage gaps. Do not assume this pair alone completely preserves every water-containing product.
Can sodium benzoate be used with vitamin C or L-ascorbic acid?
For DIY formulations, avoid combining sodium benzoate with L-ascorbic acid unless you have the expertise and testing to evaluate the system. Benzene formation has been associated with benzoate and ascorbic acid under certain formulation and storage conditions. This does not mean sodium benzoate by itself creates benzene or that ordinary citric acid should be treated as L-ascorbic acid.
Should you use sodium benzoate on sensitive skin?
Everyone's skin reacts differently when it comes to topical products and preservatives. If you have sensitive skin, patch test the finished formulation before broader use. Tolerance depends on the complete formulation, concentration, pH, and the individual.
Can I use sodium benzoate in my hair products?
It can be used as part of a suitable preservation system in hair products. Follow the supplier’s processing and storage instructions, and check that the final pH and complete preservation system are appropriate for the formula. Do not assume a universal heat limit applies to every material or product.
Other Natural Preservative Options
If Sodium Benzoate doesn't work for your formulation, check out these other natural preservative options.
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