What Is Peg-350?
Peg-350 is the short name for Poly(oxy-1,2-ethanediyl), alpha-hydro-omega-hydroxy-, a synthetic liquid made by linking together roughly 350 units of ethylene oxide. This long chain of repeating units creates a clear odorless substance that dissolves easily in water and many cosmetic oils, which makes it handy for formulators. The ingredient belongs to the large family of polyethylene glycols, better known as PEGs, first introduced to the beauty world in the late 1940s when chemists were searching for stable water-binding agents. Production starts with ethylene oxide reacting with water or glycol under heat and pressure, a controlled process that lets manufacturers choose the final chain length—in this case an average of 350 units—tailoring the material’s thickness and solubility. You will most often spot Peg-350 in lightweight moisturizers, facial masks, serums, cleansing balms, hair conditioners and rinse-off treatments where it helps keep the texture smooth and evenly blended.
Peg-350’s Cosmetic Benefits/Uses
Peg-350 offers practical benefits that improve how a product feels and performs on skin and hair.
- Binding: Helps hold together ingredients that would normally separate, so the formula stays uniform from the first use to the last
- Solvent: Dissolves both water-loving and oil-loving ingredients, letting actives spread more evenly and boosting the overall stability of the product
Who Can Use Peg-350
Peg-350 is gentle enough for most skin types including normal dry oily combination and even many sensitive skins because it rinses clean and has a low chance of clogging pores. People with a known allergy to polyethylene glycols or who have very compromised skin barriers should steer clear since irritation is possible.
The ingredient is produced synthetically so it does not rely on animal sources, making it acceptable for vegans and vegetarians as long as the finished product is certified cruelty free by the brand.
Current safety reviews rate topical Peg-350 as low risk for women who are pregnant or breastfeeding. That said this is not medical advice and anyone expecting or nursing should review any new skincare with a qualified doctor to be safe.
Peg-350 does not increase photosensitivity so it will not make skin more prone to sunburn. Always use daily sun protection anyway since other ingredients or environmental factors can still cause damage.
Potential Side Effects/Adverse Reactions
Everyone’s skin is different so reactions to Peg-350 can vary. The points below list potential side effects but these outcomes are uncommon when the ingredient is used correctly in a finished cosmetic.
- Mild skin irritation that shows up as temporary redness itching or stinging
- Rare contact allergy leading to a rash bumps or hives
- Eye irritation and watering if product accidentally gets into the eyes
- Enhanced absorption of stronger actives in the formula which may intensify their own irritation potential
If you experience any of these reactions stop using the product and consult a healthcare professional for guidance.
Comedogenic Rating
Rating: 0 / 5
Peg-350 is highly water soluble, leaves very little residue on skin and has a large molecular size that tends not to settle inside pores. Because it mainly functions as a binder and solvent rather than an occlusive agent, it does not create the oily film that can trap dead cells or sebum. For these reasons it is considered non-comedogenic and is generally suitable for people who are prone to acne or breakouts.
Most cosmetics use Peg-350 in low concentrations and the ingredient is easily rinsed off, further lowering any clogging risk.
Summary
Peg-350 works as a binder that keeps a formula mixed and as a solvent that dissolves both water based and oil based ingredients so they can spread smoothly on skin or hair. Its ability to hold everything together without adding greasiness makes it useful in light moisturizers, cleansers and hair care.
The ingredient is fairly common but not a headliner, showing up quietly in many rinse-off and leave-on products where stability and a pleasant texture are needed. Safety reviews place it in the low-risk category for topical use, with irritation or allergy being uncommon. As with any new skincare it is wise to do a small patch test first to check personal tolerance.