What Is Laureth-4 Carboxylic Acid?
Laureth-4 Carboxylic Acid is a synthetic ingredient created by reacting lauryl alcohol with ethylene oxide, then adding a carboxylic acid group. The result is a mild surfactant that mixes well with water and oils. First explored in the late 1960s when formulators were looking for gentler cleansing agents, it gained popularity as a way to boost foam without stripping skin. Production starts with coconut or palm kernel–derived lauryl alcohol, which is ethoxylated to an average of four ethylene oxide units, then carboxymethylated. This controlled process lets chemists fine-tune its solubility and cleaning power. You will spot Laureth-4 Carboxylic Acid in shampoos, body washes, facial cleansers, micellar waters, bubble baths and even some makeup removers where it helps create a creamy lather and rinses away easily.
Laureth-4 Carboxylic Acid’s Cosmetic Benefits/Uses
This ingredient has one main job in topical products.
Cleansing: Laureth-4 Carboxylic Acid lowers the surface tension of water so oils, dirt and daily grime can lift off skin or hair and rinse away. Its balanced structure gives a rich foam while remaining mild, which helps cleaners feel pleasant and leaves skin feeling fresh rather than tight.
Who Can Use Laureth-4 Carboxylic Acid
Thanks to its gentle cleansing profile, Laureth-4 Carboxylic Acid is generally suitable for normal, oily and combination skin. Dry or very sensitive skin can usually tolerate it too, but people in these groups may prefer formulas that pair it with extra moisturizers to counter any chance of tightness.
The ingredient is synthesized from plant-derived lauryl alcohol and contains no animal by-products, so it is considered vegan and vegetarian friendly.
Current data show no specific risks for pregnant or breastfeeding women when the ingredient is used in rinse-off products. That said, this is not medical advice and anyone who is pregnant or nursing should check with a healthcare provider before adding new skincare to their routine.
Laureth-4 Carboxylic Acid does not increase photosensitivity, so it will not make skin more prone to sunburn. It also plays nicely with most other cosmetic ingredients, including acids, retinoids and botanical extracts, without altering their performance.
Potential Side Effects/Adverse Reactions
Individual responses to topical ingredients differ. The effects listed below are possible yet uncommon when Laureth-4 Carboxylic Acid is used in properly formulated products.
- Mild skin irritation or redness
- Temporary dryness or tightness, especially on very dry skin
- Eye stinging if the cleanser accidentally enters the eyes
- Rare allergic contact dermatitis in people sensitive to ethoxylated surfactants
If any of these reactions occur stop using the product and consult a medical professional.
Comedogenic Rating
Rating: 1/5
Laureth-4 Carboxylic Acid is highly water soluble and designed to rinse away cleanly, so it is very unlikely to stay on skin long enough to block pores. Its molecular structure does not contain heavy oils or waxes that typically cause clogging, which is why it earns a near-zero score. Because it is usually found in rinse-off products the risk of buildup is even lower.
This makes the ingredient generally suitable for people who are prone to acne or breakouts.
Do keep in mind that the overall formula, not just a single ingredient, determines whether a product will feel greasy or leave residue.
Summary
Laureth-4 Carboxylic Acid is a mild plant-derived surfactant whose main role is cleansing. By reducing the surface tension of water it lifts oils and dirt from skin and hair then rinses them away without harsh stripping. Formulators like it because it adds a creamy foam to shampoos body washes and facial cleansers while keeping the formula gentle.
Although it is not as famous as SLS or newer sulfate-free blends it appears in a fair number of everyday cleansers thanks to its balance of foam and mildness. Safety reviews rate it as low risk when used at typical levels and irritation is rare. As with any cosmetic ingredient it is wise to do a quick patch test when trying a new product to make sure your skin agrees with it.