What Is Peg-2 Stearamide Carboxylic Acid?
Peg-2 Stearamide Carboxylic Acid is a man-made ingredient created by combining stearic acid, a fatty acid usually taken from plant oils like coconut or palm, with a small amount of ethylene oxide. The “Peg-2” part means two units of polyethylene glycol are attached, while “stearamide carboxylic acid” signals that the fatty acid has been modified to include both amide and carboxylic groups. This blend of water-loving and oil-loving parts lets the ingredient interact with both oil and water.
Chemists first explored these kinds of PEG-fatty acid hybrids in the mid-20th century when modern detergents and personal care products were booming. They were looking for milder surfactants that could clean without stripping skin. Over time the ingredient earned a spot in cosmetic labs because it helped formulas rinse away dirt yet felt gentler than old-style soaps.
To make Peg-2 Stearamide Carboxylic Acid, manufacturers start with stearic acid, convert part of it into stearamide, then react it with ethylene oxide under controlled heat and pressure. Finally they neutralize the mix to give the finished powder or paste. The result is a stable, easy-to-handle substance that blends smoothly into both water-based and oil-based mixtures.
You will usually find it in facial cleansers, body washes, micellar waters, makeup removers and sometimes in dual-phase cleansing balms. A few mild shampoos also use it for its foam-boosting help.
Peg-2 Stearamide Carboxylic Acid’s Cosmetic Benefits/Uses
The main role of Peg-2 Stearamide Carboxylic Acid in beauty products is cleansing, and it brings several perks to a formula.
- Cleansing: Its surfactant nature lifts away excess oil, makeup and daily grime so they can be rinsed off with water. Because its fatty acid tail is long and cushioning, the ingredient tends to feel less harsh than stronger detergents which helps formulas leave skin soft rather than tight.
Who Can Use Peg-2 Stearamide Carboxylic Acid
Because Peg-2 Stearamide Carboxylic Acid is a mild cleansing agent most skin types can tolerate it, including normal, oily, combination and even sensitive skin. Its cushioning fatty acid tail softens the overall formula so it is less likely to leave skin feeling tight. Very dry or compromised skin may still want richer cleansers because frequent use of any surfactant can increase dryness if not followed with moisturizer.
The ingredient itself is non comedogenic which makes it friendly for people who break out easily. It is also fragrance free and dye free in its raw form so those avoiding common irritants often do well with it.
Vegans and vegetarians can normally use products with Peg-2 Stearamide Carboxylic Acid as the stearic acid is usually sourced from coconut or palm oil. That said some suppliers still use animal derived stearic acid so anyone following a strict plant-only lifestyle should look for a clear vegan certification on the finished product.
Current safety assessments show no special restrictions for women who are pregnant or breastfeeding. The molecule is large and designed to rinse away rather than penetrate deeply into skin. Still this is not medical advice and anyone expecting or nursing should run new skincare products past a doctor to be safe.
The ingredient does not cause photosensitivity and will not make skin more prone to sunburn. It is also odorless and colorless so it plays nicely with fragranced or fragrance-free routines.
Potential Side Effects/Adverse Reactions
Side effects from topical use of Peg-2 Stearamide Carboxylic Acid differ from person to person. The points below list potential reactions but they are uncommon when the ingredient is used correctly in a finished cosmetic.
- Mild skin irritation such as redness or itching
- Dry or tight feeling if the formula is left on too long or used too often
- Stinging on very sensitive or broken skin
- Allergic contact dermatitis in people with a specific sensitivity to PEG compounds
- Eye irritation if the cleanser accidentally gets into the eyes
If you experience any of these reactions stop using the product and consult a healthcare professional
Comedogenic Rating
Rating: 1/5. Peg-2 Stearamide Carboxylic Acid is largely water dispersible thanks to its attached polyethylene glycol units, so it rinses off rather than lingering in pores. Its fatty acid tail is balanced by hydrophilic groups that keep the molecule from behaving like a pore-clogging oil. Current ingredient databases and anecdotal reports show little evidence of it causing comedones even at higher use levels.
This low score means the ingredient is generally suitable for people who are prone to acne or breakouts.
As with many PEG-based surfactants the finished product formula matters; heavy creams or balms that also contain thick occlusives could still feel greasy to some users even if this specific ingredient is low risk.
Summary
Peg-2 Stearamide Carboxylic Acid is a mild cleansing agent that lifts away oil dirt and makeup by surrounding them with its dual water-loving and oil-loving structure so they wash off easily. It cushions harsher surfactants improving skin feel and can boost foam in facial cleansers and body washes.
It is a useful yet niche ingredient; you will spot it in certain gentle cleansers but it has not reached the household-name status of classics like sodium laureth sulfate or cocamidopropyl betaine.
Safety evaluations rate it as low irritation and non-sensitizing at typical use levels. While most people can enjoy it with no issues it is always smart to patch test any new product to be sure your skin agrees.