Dr. Stacy Matthews Branch
Preservatives are used to prevent the overgrowth of microbes that can cause product deterioration. However, they must be carefully chosen to prevent harmful effects on the body. A chemical class that is widely used as a preservative in skin care products is alcohol. There are many types of alcohols, and their preservative function and effects on the skin can vary widely. Ethanol is a simple alcohol often found in skin care products, but it tends to have a drying effect on the skin depending on the amount in the product. Conversely, stearyl and cetyl alcohol do not have ethanol’s drying effect. A brief overview of the most common types of alcohols in skin care products can be found here.
The alcohol phenoxyethanol is increasingly used as a preservative to replace parabens, which have the potential to disrupt the endocrine system. Phenoxyethanol is considered a well-tolerated skin care product preservative, but there are reports of the alcohol causing irritation or allergic reactions in animals and some people. Therefore, those considered to have sensitive skin should use caution with products containing phenoxyethanol.
Phenoxyethanol is also found in plant-based skin-care products. A good example is the use of rhubarb root extract. The extract is commonly formulated in a base of water and glycerin and preserved with phenoxyethanol. Rhubarb extract contains the compound rhaponticin that has been found to provide hydration and antioxidant properties. Studies in cells grown in the laboratory suggest that rhubarb extract may be able to protect from photodamage.
Ethanolamine is another preservative found in cosmetics and is made up of a primary amine (ammonia derivative) and a primary alcohol. Ethanolamines help increase the product’s shelf life, promote the uniform blending of the product, and help remove oil and dirt from the skin. An example is the foaming agent diethanolamine found in shampoos and soaps. Diethanolamine is often excluded from some products due to the potential of this compound to react with other ingredients in products to form nitrosodiethanolamine, which may have cancer-causing properties. All alcohols are not created equal and a better understanding skin care product alcohols will help you to make a conscious choice of what to use on your skin. Fortunately, water-based, enzymatic products exist that can provide an effective, non-drying skin cleansing alternative.
- Dréno B, Zuberbier T, Gelmetti C, Gontijo G, Marinovich M. Safety review of phenoxyethanol when used as a preservative in cosmetics. J Eur Acad Dermatol Venereol. 2019 Nov;33 Suppl 7:15-24
- Fiume MM, Heldreth B, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler DC, Marks JG Jr, Shank RC, Slaga TJ, Snyder PW, Andersen FA. Safety Assessment of Diethanolamine and Its Salts as Used in Cosmetics. Int J Toxicol. 2017 Sep/Oct;36(5_suppl2):89S-110S
- Silveira JP, Seito LN, Eberlin S, et al. Photoprotective and antioxidant effects of Rhubarb: inhibitory action on tyrosinase and tyrosine kinase activities and TNF-α, IL-1α and α-MSH production in human melanocytes. BMC Complement Altern Med. 2013;13:49.
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