Benzoic Acid in Personal Care

Benzoic acid is a popular preservative in personal care products, thanks to its excellent antibacterial and antifungal properties.
5 min read

One of the most significant challenges involved in formulating skin care and cosmetics is ensuring shelf life. No consumer wants to open a product to find mold or experience a product going “off” after a month or two of use. Product formulators are always on the hunt for effective and safe preservatives. Benzoic acid and its derivatives feature excellent antibacterial and antifungal properties, making them a popular preservative in the formulation of personal care products.

While some people have an allergy to benzoic acid, it’s generally well-tolerated when used topically in appropriate concentrations. However, most chemists recommend using it in combination with other preservatives for best performance.

What is Benzoic Acid?

Benzoic acid is a white, crystalline organic compound and member of the carboxylic acid family. Synonyms of benzoic acid include benzenecarboxylic acid, carboxybenzene, and benzoate. It’s widely used in the manufacture of various cosmetics, dyes, and plastics as well as in topical antifungals and insect repellants. The compound is also used as a food preservative since it effectively inhibits the growth of bacteria and molds in foods with an acidic pH value. This article will focus on the use of benzoic acid in personal care products.

benzoic acid chemical structure illustration
Benzoic acid chemical structure. Source: Wikipedia

How is benzoic acid produced?

Benzoic acid is found naturally in gum benzoin, a resin found in the bark of trees in the genus Styrax. However, most benzoic acid today is synthetically produced through the air oxidation of toluene, which avoids the problem of product contamination.

Benzoic acid vs. sodium benzoate

Sodium benzoate is a water-soluble salt obtained from benzoic acid. Although undissociated benzoic acid is more effective for preservation purposes, some product formulators prefer sodium benzoate since its water solubility is about 200 times higher than benzoic acid’s.

Benzoic Acid Applications in Personal Care Products

The properties of benzoic acid make it useful in skin care and cosmetic formulations in three specific ways. When these benefits are combined, benzoic acid is equipped to improve product quality.


Benzoic acid, as well as its salts and esters, are used as preservatives in skin care and cosmetic products, with a maximum concentration of 0.5 %, (calculated as acid), as regulated by the EU Cosmetics directive 76/768/EEC.

pH Adjuster

As a product stabilizer, benzoic acid helps to regulate pH and protect the integrity of ingredients.

Moisture Retention Aid

Topical application of benzoic acid may play a role in reinforcing skin barrier function, thus promoting the skin’s ability to retain moisture.

Product Examples

Here are a few examples of Benzoic acid applications in skin care, hair care, and cosmetics products:

Hair CareShampoos, Conditioners, Styling Products
Body & Face CareCleansers, Hand Soaps, Toners, Gels, Lotions, Creams
CosmeticsFoundations, Eyeliners, Mascaras, Powders, Wipes
Sun ProductsSunscreens, Suntans, Aftersuns
Bath ProductsShower Gels, Bubble Baths, and Intimate Wipes

Properties of Benzoic Acid

Appearance at 25 °CWhite Crystals
pH (1% Aqueous)4
Molar Mass122.12 g/mol
Viscosity, cps at 25°C60-75
SolubilitySlightly soluble in water, Freely soluble in ethanol
OdorOdorless or with a slight benzaldehyde odor
Melting Point122 ºC
Boiling Point249 ºC
Shelf Life24-36 months

Typical Formulations


Here’s an example of how a shampoo product formulation table containing sodium hyaluronate:  

PhaseTrade NameINCI Name% Wt.
A – Deionized Water
– Hyaluronic Acid BT
– Vegetable Glycerin
– Glutange Grano
– Rosmarin Glyceric extract

– Natural Extract AP
– Viscarin GP 209
– Aqua
– Sodium Hyaluronate
– Glycerin
– Hydrolyzed Wheat Protein
– Rosmarinus officinalis Extract + Glycerine
– Betaine
– Chondrus crispus Extract Algae

BAndean QD Ultra (25% Aq.Sol.)Quillaja saponaria Extract+Aqua8.00
CPlantacare 818 UPCoco Glucoside18.00
DCitric AcidCitric Acid0.26
E– Phenoxyethanol
– Benzoic Acid
– Plantacare 818 UP
– Phenoxyethanol
– Benzoic Acid
– Coco Glucoside

Benzoic Acid Formulation Considerations

  • Benzoic acid is incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. 
  • It is not recommended to be used along with the extremely alkaline systems like Hair Color, Perming formulations

Formulators recommend a maximum concentration of:

  • 2.5% for non-preservative purposes in cosmetic rinse-off products
  • 1.7% in cosmetic oral-care products
  • 0.5%in leave-on products

Acetic acid sometimes serves similar functions in personal care products, such as pH adjustment and microbial growth inhibition. However, benzoic acid (and its salts) is more commonly utilized as a preservative in this context.

Benzoic Acid Safety & Regulatory Considerations

  • GRAS listed. 
  • Included in the FDA Inactive Ingredients Database (IM and IV injections, irrigation solutions, oral solutions, suspensions, syrups and tablets, rectal, topical, and vaginal preparations).
  • Included in nonparenteral medicines licensed in the UK. 
  • Included in the Canadian List of Acceptable Non-medicinal Ingredients.
  • While low concentrations of benzoic acid are considered non-toxic, and the Environmental Protection Agency classifies it as noncarcinogenic, significant exposure can cause a variety of health issues. 
  • The European Chemicals Agency has stated that benzoic acid causes damage to organs through prolonged or repeated exposure and can cause serious eye damage and skin irritation. 
  • Additionally, the National Oceanic and Atmospheric Administration has noted that benzoic acid has the potential for environmental damage if released. For this reason, benzoic acid should be stored in sealed containers in a cool, dry, and well-ventilated place, away from heat, any source of ignition, and all incompatible substances. 
  • Should be kept away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, caustics, ammonia, amines, isocyanates. 
  • Certain states may require benzoic acid to be contained and disposed of as hazardous waste.

Identification Numbers

CAS Number65-85-0
EC Number200-618-2

Fun Facts About Benzoic Acid

  • Benzoic acid was first described by Nostradamus in the 16th century as he explained the dry distillation of gum benzoin (a resin found in trees)
  • Benzoic acid is commonly used to form the “snowflakes” in snow globes 
  • Benzoic acid occurs naturally in many plants
  • In the early 20th century, benzoic acid was used as an analgesic and antiseptic