What Is Peg-35 Stearate?
Peg-35 Stearate is a synthetic ingredient made by attaching about 35 units of ethylene oxide to stearic acid, a fatty acid most commonly sourced from vegetable oils like coconut or palm. The result is a waxy, white to off-white solid that blends water-loving and oil-loving parts in one molecule. This dual nature is what makes it so useful in personal care.
The cosmetic industry first explored polyethylene glycol (PEG) derivatives in the 1950s when formulators looked for safer, more versatile alternatives to soap-based emulsifiers. Over time Peg-35 Stearate proved reliable, gentle and easy to work with, leading to its widespread adoption in creams and lotions by the 1970s.
Manufacturing begins with purified stearic acid that undergoes a process called ethoxylation. Under controlled heat and pressure, ethylene oxide gas reacts with the acid, adding the desired number of ethylene glycol units. The finished material is then filtered and tested for purity before heading to blending tanks where it is incorporated into finished formulas.
You will most often find Peg-35 Stearate in facial moisturizers, body lotions, cleansing milks, makeup removers, sheet masks, sunscreens and anti-aging serums. Its balanced structure lets it keep oily and watery ingredients together, creating smooth, stable products that feel light on the skin.
Peg-35 Stearate’s Cosmetic Benefits/Uses
This ingredient brings a couple of key technical perks to a formula that translate into an improved user experience
- Cleansing: The molecule’s water-attracting head and oil-loving tail allow it to grab onto dirt, excess sebum and makeup so they can be rinsed away easily. This helps cleansers work effectively while staying mild on the skin
- Emulsifying: Peg-35 Stearate keeps oil and water mixed evenly, preventing separation over time. A stable emulsion means creams stay silky, lotions remain fluid and active ingredients are delivered consistently with each use
Who Can Use Peg-35 Stearate
Peg-35 Stearate is considered gentle enough for most skin types, including dry, normal, combination and oily. Because it helps maintain a stable formula without leaving a greasy film, people prone to clogged pores often appreciate its lightweight feel. Those with very sensitive or severely compromised skin conditions such as active eczema may notice mild irritation if a product contains a high percentage of PEGs, so patchy or inflamed areas could benefit from extra caution.
The stearic acid used to create Peg-35 Stearate is typically sourced from plant oils which makes the finished ingredient suitable for vegetarians. Strict vegans should double-check with the brand because stearic acid can also be obtained from animal fat in some supply chains.
Peg-35 Stearate is not known to interfere with pregnancy or breastfeeding when applied topically in cosmetic amounts. While current safety assessments deem it low risk, this is not medical advice and women who are pregnant or nursing should run any skincare routine past a qualified healthcare professional to be on the safe side.
The ingredient does not cause photosensitivity so it will not make skin more vulnerable to sunburn. It is also fragrance-free and compatible with common actives like niacinamide or non-ionic sunscreens, making it versatile for layered routines.
Potential Side Effects/Adverse Reactions
Reactions to topical Peg-35 Stearate vary from person to person. The following points describe potential side effects that could occur though most users will not experience them when products are formulated correctly.
- Transient redness or mild stinging on very sensitive skin
- Contact dermatitis in individuals with a known PEG allergy
- Eye irritation if the product accidentally gets into the eyes
- Enhanced absorption of other ingredients which could amplify their irritating effects
If you notice any of these issues stop using the product and seek advice from a medical professional.
Comedogenic Rating
Rating: 1 / 5 Peg-35 Stearate carries a low risk of clogging pores because the polyethylene glycol part of the molecule is highly water soluble, which helps residues rinse away instead of building up inside follicles. While pure stearic acid sits around a 2 – 3 on the scale, the ethoxylation process makes the finished ingredient far less occlusive. For most acne-prone users this means Peg-35 Stearate is unlikely to trigger breakouts, though final results always depend on the overall formula and how thoroughly the product is removed. Very heavy creams with multiple waxy agents could still pose a risk, so evaluate the entire ingredient list rather than this emulsifier alone.
Summary
Peg-35 Stearate acts as both a cleanser and an emulsifier. Its oil-loving stearic acid tail grabs onto makeup and sebum while the water-loving PEG chain lets those oils disperse in water, creating stable, silky textures that rinse clean. Thanks to this dual action it shows up in everything from lightweight lotions to rich night creams, though it is not as headline-grabbing as newer plant-derived emulsifiers and therefore stays mostly behind the scenes in modern formulas.
Safety reviews label it low risk for irritation or sensitization when used at typical cosmetic levels, and real-world reports back that up. As with any new skincare ingredient it is smart to patch test a product first to make sure your individual skin tolerates it well.