Polyethylene Glycol (PEG) is one of the most commonly used synthetic ingredients in personal care and skincare formulations. It serves multiple functions, acting as a humectant, solvent, penetration enhancer, and emulsifier. However, despite its widespread use, PEG compounds have generated debate within the skincare and cosmetic industries due to concerns about contamination, skin penetration, and environmental impact.
This article takes an in-depth look at PEG, including its chemical nature, how it is manufactured, why it is used in skincare, and how it affects consumers.
Polyethylene Glycol is a petroleum-derived polymer composed of repeating ethylene oxide units. It exists in various molecular weights, which determine its consistency and function in formulations. Low molecular weight PEGs are liquid, while high molecular weight PEGs have a thick, waxy consistency.
PEGs are usually listed in ingredient lists with a number (e.g., PEG-100, PEG-40) that indicates their molecular weight. Higher numbers mean heavier molecules, which have different solubility and texture-modifying properties.
PEG is classified as a polyether, with the general chemical formula:
H−(O−CH₂−CH₂)ₙ−OH
Where "n" represents the number of ethylene oxide units, which affects its physical properties.
PEG is produced through the polymerization of ethylene oxide, an industrial chemical derived from petrochemicals. The process typically involves:
During manufacturing, ethylene oxide and 1,4-dioxane, both of which are classified as potential carcinogens, may be formed as by-products. The purification process aims to reduce these contaminants, but there have been concerns about residual amounts remaining in consumer products.
PEGs serve a variety of functions in skincare and personal care formulations, making them a preferred ingredient for formulators. Some of the most common roles of PEGs in cosmetics include:
PEG acts as a humectant, helping skincare products retain moisture by drawing water to the skin’s surface. This is particularly useful in lotions and creams designed for hydration.
PEGs enhance the solubility of active ingredients, ensuring that oils, vitamins, and other components mix evenly into formulations.
One of the most controversial aspects of PEGs is their ability to enhance skin penetration. By disrupting the skin barrier, PEGs allow active ingredients to absorb deeper into the skin, increasing their efficacy. However, this also raises concerns about the potential penetration of harmful substances.
PEGs help oil and water mix in emulsions, allowing creams and lotions to maintain a stable consistency. PEGs also function as surfactants in cleansers, helping remove dirt and oil from the skin.
Higher molecular weight PEGs provide a silky, smooth feel to lotions and creams, improving their spreadability and sensory appeal.
While PEGs improve product stability and performance, their impact on human health and safety is a subject of ongoing discussion. Here’s a closer look at some key consumer concerns:
PEGs' penetration-enhancing properties raise concerns about skin barrier integrity. In compromised or damaged skin, such as wounds, PEGs can facilitate the absorption of harmful chemicals or contaminants that may be present in a formulation.
PEGs are generally considered non-irritating at normal usage levels. However, individuals with sensitive skin or existing skin conditions (such as eczema or rosacea) may experience irritation, especially when exposed to PEGs with lower molecular weights.
A major concern with PEGs is contamination with:
Reputable manufacturers use purification methods to remove these contaminants, but trace amounts have been found in some consumer products. The U.S. Food and Drug Administration (FDA) and European Union (EU) regulate the levels of 1,4-dioxane in cosmetics, but there are no mandatory testing requirements in the U.S.
PEGs are not fully biodegradable, which means they can contribute to water pollution. Their widespread use in rinse-off products (such as cleansers and shampoos) has raised concerns about their accumulation in wastewater and potential effects on aquatic life.
Because PEGs increase skin permeability, they can enhance both the effectiveness and risks of active ingredients. This means that if a product contains irritants, allergens, or other questionable substances, PEGs could facilitate their deeper absorption, amplifying their impact.
Regulatory agencies around the world have assessed the safety of PEGs:
The Cosmetic Ingredient Review (CIR) Expert Panel has deemed PEGs safe for use in cosmetics, provided they are properly purified.
The decision to use or avoid PEG-containing skincare products depends on individual preferences and concerns:
Consumers looking to minimize risk should choose brands that disclose their purification processes and use low-penetration PEGs (higher molecular weight PEGs).
Polyethylene Glycol (PEG) is a widely used but controversial skincare ingredient. While it provides essential formulation benefits such as emulsification, hydration, and enhanced absorption, it also carries potential risks due to contaminant exposure, skin barrier disruption, and environmental persistence.
Ultimately, informed consumers should weigh the benefits and risks when selecting PEG-containing products. For those concerned about purity, looking for brands that adhere to stringent quality controls or opting for PEG-free alternatives may be a safer choice.
As consumer demand for clean beauty and transparency continues to rise, the future of PEGs in skincare formulations will likely evolve, with a push toward safer, plant-based, and biodegradable emulsifiers.