What Is Peg-36 Stearate?
Peg-36 Stearate is a man-made ingredient created by joining stearic acid, a fatty acid usually taken from vegetable oils like coconut or palm, with polyethylene glycol that contains an average of 36 repeating units. The result is a waxy powder or flake that dissolves easily in water and oil, helping the two mix when they normally would not.
The compound was first explored in the 1950s when chemists looked for gentler alternatives to soap. By reacting refined stearic acid with measured amounts of ethylene oxide under heat and pressure they made a stable ester that offered the mild cleansing of fatty acids plus the solubility of polyethylene glycol. Over time this balance of oil-friendly and water-friendly parts made Peg-36 Stearate a common helper in cosmetics.
Today you will spot it in facial cleansers, makeup removers, moisturizers, sunscreens, sheet masks, hair conditioners and even some lightweight serums. Any formula that needs a smooth lotion-like feel or low-foam cleansing action may lean on this versatile ingredient.
Peg-36 Stearate’s Cosmetic Benefits/Uses
Peg-36 Stearate serves more than one role in personal care formulas, giving chemists flexible options when designing products.
- Cleansing: Its mix of water-loving and oil-loving parts lifts away dirt, makeup and excess sebum without the harshness of traditional soap so skin feels fresh yet comfortable
- Emulsifying: Acts as a bridge between oil and water phases, creating stable creams and lotions that stay smooth, resist separation and spread evenly on the skin
Who Can Use Peg-36 Stearate
Peg-36 Stearate is gentle enough for most skin types including normal, dry, combination and oily skin. Its mild cleansing action removes grime without stripping natural oils so even sensitive or mature skin usually tolerates it well. Those with very reactive or allergy-prone skin should still check the full ingredient list since irritation can come from other parts of the formula.
The stearic acid used to make Peg-36 Stearate is often sourced from plant oils such as coconut or palm which makes it suitable for vegans and vegetarians. Some suppliers can use animal-derived fat so anyone following a strict plant-based lifestyle should look for brands that clearly label the ingredient as vegetable origin.
No safety issues have been flagged for pregnant or breastfeeding women when Peg-36 Stearate is applied to the skin. This information is not medical advice and expecting or nursing mothers should run any skincare routine past a doctor to be safe.
The ingredient does not increase photosensitivity so it will not make the skin more prone to sunburn. It can be used day or night alongside sunscreen in the morning. There are no known interactions with common actives such as retinol, vitamin C or alpha hydroxy acids.
Potential Side Effects/Adverse Reactions
Reactions to topical Peg-36 Stearate vary from person to person. The effects listed below are only potential issues and most users will not notice any problems when the ingredient is used at standard levels in a well-made product.
- Mild redness or stinging in very sensitive skin
- Rare allergic contact dermatitis if the user is specifically allergic to polyethylene glycol compounds
- Eye irritation if a product containing high levels of Peg-36 Stearate accidentally gets into the eyes
- Dryness if combined with other strong cleansing agents and overused
If any discomfort, rash or lasting irritation occurs stop using the product and seek advice from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1/5. Peg-36 Stearate is derived from a fatty acid yet its large size and the presence of multiple polyethylene glycol units make it water dispersible rather than pore clogging. It rinses away easily and does not build up inside follicles which keeps the risk of blocked pores low. This mild nature means it is generally suitable for acne-prone or breakout-prone skin, especially when used in rinse-off cleansers or well-balanced leave-on formulas. Because every complexion is different, people with extremely reactive or congestion-prone skin should still observe how their skin responds when first adding a new product.
Summary
Peg-36 Stearate is chiefly a cleansing and emulsifying agent. Its fatty stearic acid half grabs onto oils and dirt while the polyethylene glycol half mixes readily with water, letting products lift grime off the skin and keeping oil-and-water blends stable and silky. This dual character explains why it appears in everything from gentle face washes to light moisturizers.
It is not a headline-grabbing ingredient but formulators appreciate its reliability so you will quietly find it in many mainstream and indie products. Safety studies and decades of cosmetic use show a very low risk profile, with irritation or allergy reported only rarely. As with any new skincare step, patch test first to make sure your own skin stays comfortable.