Science
Mechanism of Action
As a polyethylene glycol, PEG-500 operates by forming hydrogen bonds with water molecules, effectively drawing and retaining moisture to the skin for prolonged hydration. It also reduces transepidermal water loss by creating a protective barrier. Functioning as a solvent, emulsifier, and emollient, it serves as a vehicle to facilitate the penetration and delivery of other active ingredients into the skin, while also refining product texture.
Research
Clinical Evidence
High confidence20%
Transparency
Dusting Analysis
The Formula
Formulation
Stability
PEG solutions exhibit optimal stability when stored frozen at -20°C, with refrigerated storage at 4°C offering greater stability than room temperature. Degradation, which involves increased levels of aldehydes, carboxylates, peroxides, elevated ionic strength, and reduced pH, is accelerated by warm temperatures, light, and oxygen exposure. Minimizing oxygen contact (e.g., via argon purging) and protecting from light can help preserve formulation integrity.
Synergies
- Acts as an effective vehicle to enhance the delivery and penetration of other active ingredients into the skin.
Conflicts
- Avoid use on damaged or disrupted skin, such as second or third-degree burns, due to a significant increase in absorption potential and a risk of kidney toxicity.
- Sonication may lead to degradation of PEG-500, potentially generating byproducts that could be toxic to mammalian cells.
- Can cause cross-sensitization in individuals sensitive to other structurally similar PEG derivatives (e.g., PEG ethers, PEG fatty acid esters).
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) Expert Panel has affirmed the safety of PEG ingredients for use in cosmetic products, noting low oral and dermal toxicity. Lower molecular weight PEGs are minimally absorbed, and higher molecular weight PEGs (PEG-75 and above) are not absorbed through intact skin. While generally minimally irritating and non-sensitizing, a small risk of sensitivity with continued use may exist for some individuals. Concerns regarding potential contamination by ethylene oxide (a known carcinogen) and 1,4-dioxane (a possible carcinogen) during manufacturing are recognized, though adherence to stringent purification standards in high-quality formulas is expected to control these byproducts. The FDA has approved polyethylene glycol for use in food, cosmetics, and pharmaceuticals.
Your Skin
Skin Compatibility
Our Assessment
Verdict
PEG-500 is a valuable, multi-functional ingredient that effectively hydrates the skin and enhances active ingredient delivery, provided it is used on intact skin and sourced from high-purity formulations.
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