How to Prevent Contamination in Cosmetic Products? Why cosmetic products need to be preserved?

Cosmetic products become easily contaminated by bacteria, fungi and other microbes. Containing water, oils, peptides, and carbohydrates cosmetics are a very good medium for growth of microbes.

And these tiny organisms bring with them some distasteful product changes or even disease. You typically would adding preservatives to your formulas. You have to know which preservatives are highly regulated and restricted ingredients.

Why you need cosmetic preservatives 

Preservation of cosmetic products is important to ensuring their safety and shelf stability. There are two primary reasons you need preservatives.
1. To stop microbes from spoiling your products.
2. To stop microbes from causing disease and infection of the skin.

The microbes that can infect your formulas primarily include bacteria, mold, and yeast. In small quantities they don’t represent much of a problem but when they multiply, look out. Bacteria like Pseudomonas can cause all kinds of health problems including skin and eye infections, toxic shock, strep throat, and even food poisoning. Yeast like Candida albicans can cause thrush. And many other bacteria can cause your products to smell awful, change color or otherwise break down.

In addition to natural and chemical preservatives, pH adjustment can be used to keep cosmetics germ-free. It is important to note, however, that very high or low pH values that keep microbial growth at bay may prove irritating to the skin or mucous membranes.


The following is a list of common preservatives used in cosmetic and personal care products. As a future (or current) formulator, you will undoubtedly be using many of them.

Parabens (Methylparaben, Ethylparaben, Propylparaben, Butylparaben, Isobutylparaben)
Parabens are the most commonly used preservatives. They are derivatives of p-hydroxybenzoic acid. They are typically supplied as powders and can sometimes be difficult to incorporate into a system due to the water solubility limitations. They are effective against a broad spectrum of bacteria and fungi. They do have pH limitations and are not effective against all microbes so you usually will need an additional preservative.

Formaldehyde donors
These compounds interfere with membrane proteins which kills microbes. They are effective against bacteria, fungi, and mold. Instead ingredients that dissociate into formaldehyde when put in a water solution are used. These are compounds like DMDM Hydantoin, Imidazolidinyl Urea, and Gluteraldehyde. They are most often used in surfactant systems.

Phenol derivatives (Phenoxyethanol) 
Phenol derivatives have been used in cosmetics for many years and can be effective against a range of microbes. Unfortunately, they are not as effective as the previous ingredients so their use is limited.

Quats (Benzalkonium Chlroide, Methene aommonium chloride, and Benzethonium chloride)
Compounds that contain nitrogen and have a positive charge when placed in solution are called quaternary compounds (or quats). Many of them demonstrate an ability to kill microbes. Their cationic nature makes them less compatible with anionic surfactants which limits their application & use.

Alcohol (benzyl alcohol, dichlorobenzyl alcohol, propylene glycol)
 Ethanol is a great preservative but you need to use it in high levels and it faces significant environmental restrictions. In lower levels, these compounds are less effective at preserving products.

Isothiazolones (Methylchloro- Isothiazolinone and Methyl-Isothiazolinone)
These Synthetic compounds are effective at incredibly low levels. They have been shown to work at a wide range of pHs and in many different formulas. There use has been stymied however, by at least one study that suggested it could cause skin sensitization.

Organic Acids and Other
Sodium Benzoate, Chloracetamide, Triclosan, and Iodopropynyl Butylcarbamate, Salicylic Acid, Potassium Sorbate, DMDM Hydantoin, Sodium benzoate, Chlorphenism, Diazolidinyl Urea, Sorbic Acid, Methylisothiazolinone, Sodium Dehydroacetate, Dehydroacetic Acid, Quaternium – 15, Stearalkonium Chloride, Zinc Pyrithione, Sodium Metabisulfite, 2-Bromo-2-Nitropropane, Chlorhexidine Digluconate, Polyaminopropyl biguanide, Sodium Sulfite, Sodium Salicylate, Citric Acid, Grapfruit Seed Extract, Neem Oil, Essential Oils (various), Lactic Acid, Vitamin E (tocopherol). Pyridine derivatives like Sodium pyrithione and zinc pyrithione are used to kill the bacteria that causes dandruff.

The chemicals (both natural and synthetic) listed above perform differently in different cosmetic and personal care products. Some will require levels of only 0.1%, while others will require levels up to 5% to properly preserve the product.

Preservatives are designed to kill cells and they are very effective. That’s make preservative also potentially hazardous. They don’t easily discriminate between good human cells and bad microbial cells. But ultimately, the risk from using preservatives is significantly lower than that of using unpreserved cosmetics. All chemicals can be deadly if you’re exposed to a high enough level.

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