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PEGs and Stearic Acid: Everything You Need to Know About This Common Skin Care Ingredient

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PEGs and stearic acid are ingredients commonly used in skin care products. There has been much confusion in the media regarding their safety.   They have even been linked to claims about organ toxicity and contamination. Read on for everything you need to know about this common skin care ingredient. Here are a few frequently asked questions and their answers.

Q.  What exactly is a PEG?

A.  PEG stands for polyethylene glycol. They are derived from natural oils such as palm and coconut oils and are often combined with stearic acid in skin care products.

Q.  What is stearic acid?

A.  Stearic acid is a natural fatty acid usually derived from vegetable oil.

Q.  What does the number mean?

A.  The number typically identifies the weight of the PEG. For example, PEG 100 stearate means that polyethylene glycol has an approximate molecular weight of 100 and is chemically attached to stearic acid. Size does matter and impacts its role or function. For example, PEG 3350 (aka Miralax) is used as a laxative to treat constipation while PEG 4 is used as a skin moisturizer. PEG 100 and PEG 150 are most commonly used in cosmetics.

Q.  What are PEGs’ uses in skin care?

A.  PEGs are used in skin care as emollients and emulsifiers. When making a skin care product, ingredients cannot simply be mixed together and be expected to stay mixed up nicely. To avoid a product from being too watery or from separating out (particularly the oil and water) and to ensure the moisturizing function of the product, PEGs such as PEG 100 serve both as an emollient and an emulsifier. An emollient helps to soften the skin. An emulsifier allows the product to stay “mixed-up” and preserves its texture and function. Emulsifiers are particularly important to keep water-based and oil-based mixtures stable in their presentation and function.

Q.  Are they safe for skin care?

A.  Yes, PEGs are safe for use in skin care products, and they have been used in skin care products for a long time and have been studied for years. Their safety has been well-documented for topical use (Fruijtier-Pollot, 2005) despite what other sources may say.

Q.  I have heard that PEGs contain the same ingredients as antifreeze. Is this true?

A.  PEGs are NOT antifreeze. Antifreeze is composed of ethylene glycol – not polyethylene glycol. So, although the names appear similar to one another, these two chemicals have very different properties and functions. Ethylene glycol is toxic and polyethylene glycol is not.

Be cautious on what you read and on the marketing of natural products. Ensure that the sources you are reading are credible. The most important thing for skin care is safety. A product’s safety can be proven through clinical testing with third-party unbiased dermatologists. This will reveal any allergy or irritancy in the product.   All Baby Pibu™ products have been through clinical testing and have been shown to be hypoallergenic and irritant-free.

For more information on skin care, read our blog.

Check for information on our products, including their ingredient list.


Fruijtier-Polloth, C. “Safety assessment on polyethylene glycols (PEGs) and their derivatives as used in cosmetic products.” Toxicology 214 (2005) 1-38.


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