What Is Sodium Isosteareth-6 Carboxylate?
Sodium Isosteareth-6 Carboxylate is a synthetic surfactant produced by reacting isostearyl alcohol with ethylene oxide to attach roughly six ethoxy units, then carboxymethylating the end of the chain and neutralizing it with sodium hydroxide. The result is a salt that has both water-loving and oil-loving parts, making it useful for mixing ingredients that do not normally stay blended. The raw materials start from fatty alcohols derived from plant oils or sometimes petrochemical sources, then go through the ethoxylation and carboxylation steps under controlled conditions in stainless steel reactors.
The ingredient emerged in the late 1980s when formulators were looking for milder alternatives to traditional sulfates. Its balanced structure offered good cleansing power without the strong stripping feel of harsher surfactants. Over time it became popular in gentle facial cleansers, baby washes and modern sulfate-free shampoos.
Today you will most often find Sodium Isosteareth-6 Carboxylate in foaming face washes, micellar waters, hydrating body washes, sulfate-free shampoos, makeup removers, light lotions and some cream-to-foam masks. It is valued for keeping formulas stable while providing a soft, creamy lather.
Sodium Isosteareth-6 Carboxylate’s Cosmetic Benefits/Uses
Formulators choose this ingredient for two main reasons:
- Cleansing: Its surfactant nature lifts away dirt, excess oil and makeup while rinsing off easily with water, leaving skin or hair feeling fresh but not tight.
- Emulsifying: By bridging water and oils it helps creams, lotions and cleansers stay uniform so the product does not separate over time, improving texture and shelf life.
Who Can Use Sodium Isosteareth-6 Carboxylate
This mild surfactant is generally suitable for all skin types. Oily and combination skin benefit from its effective yet gentle cleansing, while normal and dry skin usually tolerate it well when paired with moisturising ingredients. Even sensitive skin can often use it because it lacks the harshness of sulfates, though people with a severely compromised barrier may still prefer extra-mild formulas.
The ingredient is considered vegan and vegetarian friendly because it is synthetically produced from plant-derived or petrochemical raw materials, with no animal derivatives involved in the final compound.
No specific warnings exist for pregnant or breastfeeding women regarding topical use of Sodium Isosteareth-6 Carboxylate. It is not known to penetrate deeply or act systemically, but this is not medical advice and anyone who is pregnant or nursing should run any skincare product past a doctor just to be on the safe side.
Sodium Isosteareth-6 Carboxylate does not increase photosensitivity, so it will not make skin more prone to sunburn. It is also colour safe for hair products and is compatible with both rinse-off and leave-on formulas.
Potential Side Effects/Adverse Reactions
Responses to topical Sodium Isosteareth-6 Carboxylate vary from person to person. The points below list potential side effects, but most users will not experience them when the ingredient is properly formulated and used as directed.
- Mild skin irritation such as redness or itching
- Temporary stinging on very sensitive or broken skin
- Dryness or tightness if used in high concentrations without added moisturisers
- Rare allergic contact dermatitis in individuals with specific sensitivities
- Eye irritation if the product accidentally gets into the eyes
If you notice any of these reactions stop using the product and consult a healthcare professional if irritation persists.
Comedogenic Rating
Rating: 1/5. Sodium Isosteareth-6 Carboxylate is a water-soluble surfactant that rinses away cleanly rather than sitting on the skin or clogging pores. It lacks heavy oils or waxy residues that normally raise comedogenicity. Trace amounts left after rinsing are unlikely to obstruct follicles, earning it a very low score.
Because of this low rating it is generally considered safe for people prone to acne or breakouts.
Formulas that combine the ingredient with heavy butters or occlusives could raise the overall pore-clogging potential, so the final product matters more than the single raw material.
Summary
Sodium Isosteareth-6 Carboxylate acts as both a cleanser and an emulsifier. Its dual water-loving and oil-loving structure lifts dirt, makeup and excess sebum while helping water and oil phases stay blended, keeping lotions and washes smooth and stable.
Although not a household name like sulfates or coco-glucoside, it enjoys steady popularity in modern gentle cleansers and sulfate-free shampoos where consumers look for mild yet effective options.
Safety data show it is well tolerated by most skin types, with only rare irritation reports. As with any new skincare ingredient it is smart to do a quick patch test when trying products that contain it just to be on the safe side.