What Is Sodium C9-11 Pareth-6 Carboxylate?
Sodium C9-11 Pareth-6 Carboxylate is a synthetic surfactant made by reacting fatty alcohols derived from coconut or palm oil with ethylene oxide, then further modifying the molecule to add a carboxylate (salt) group. The result is a water-soluble ingredient that belongs to the family of ether carboxylic acids. First explored in the late twentieth century as formulators searched for gentler alternatives to traditional sulfates, it gained popularity because it cleans well without stripping skin or hair.
Production starts with medium-chain fatty alcohols that contain nine to eleven carbon atoms. These alcohols undergo ethoxylation, where an average of six ethylene oxide units attach to each molecule. The intermediate is then carboxymethylated and neutralized with sodium hydroxide, yielding the final sodium salt. This multi-step process creates a mild, biodegradable surfactant that works in a wide pH range.
You will most often spot Sodium C9-11 Pareth-6 Carboxylate in liquid cleansers such as shampoos, body washes and facial cleansers. It is also used in micellar waters, make-up removing wipes, exfoliating scrubs, bubble baths and some lightweight moisturizers where a touch of foaming action or emulsification is desired.
Sodium C9-11 Pareth-6 Carboxylate’s Cosmetic Benefits/Uses
Formulators choose this ingredient because it offers multiple performance benefits in water-based products
- Cleansing: Lowers surface tension so oil, dirt and product buildup can be lifted and rinsed away easily. Produces a soft creamy lather that feels gentle yet effective on skin and hair
- Emulsifying: Helps mix oil and water phases, keeping formulas stable and uniform which prevents separation in products like cleansing oils or two-in-one shampoos
Who Can Use Sodium C9-11 Pareth-6 Carboxylate
This gentle surfactant suits most skin types including oily, combination, normal and even sensitive skin because it cleans without the harsh stripping sometimes linked to sulfates. People with very dry or eczema-prone skin may still prefer to pair it with richer emollients since any cleanser can contribute to dehydration if overused.
The ingredient is produced from plant-derived fatty alcohols and synthetic processing steps with no animal-derived substances, so it is suitable for both vegans and vegetarians. Of course finished product claims depend on the brand’s overall formulation and cruelty-free policies.
Current safety data indicate no specific risks for pregnant or breastfeeding women when the ingredient is applied topically in rinse-off formulas. Absorption through intact skin is minimal. This is not medical advice and anyone who is pregnant or nursing should discuss skincare choices with a healthcare professional to be safe.
Sodium C9-11 Pareth-6 Carboxylate does not cause photosensitivity, so daytime use does not require extra sun precautions beyond a normal broad-spectrum sunscreen routine.
Potential Side Effects/Adverse Reactions
Responses to topical Sodium C9-11 Pareth-6 Carboxylate vary from person to person. The points below outline potential side effects that could occur, though they are uncommon when the ingredient is used correctly in a finished cosmetic product.
- Mild skin irritation – may present as temporary redness or stinging, more likely in very sensitive or compromised skin
- Deye irritation – contact with eyes can cause tearing or burning until thoroughly rinsed
– excessive or prolonged cleansing without following with moisturiser can strip natural oils - Allergic contact dermatitis – rare sensitisation leading to itching, rash or swelling
If any adverse reaction develops discontinue use immediately and consult a healthcare professional for guidance.
Comedogenic Rating
Rating: 0/5 (non-comedogenic). Sodium C9-11 Pareth-6 Carboxylate is highly water soluble and does not leave an occlusive film on skin. Its molecules rinse away completely so they are unlikely to clog pores or trap oil and debris. Because it functions mainly in rinse-off cleansers and micellar formulas, contact time with skin is short, further reducing any risk of pore blockage.
Suitable for acne-prone and breakout-prone skin.
No specific data suggest it worsens fungal acne. As always overall formula composition and personal tolerance play a role.
Summary
Sodium C9-11 Pareth-6 Carboxylate works as a mild cleanser and secondary emulsifier. By lowering surface tension it lifts oil, sweat and product residue so they rinse away easily. Its ethoxylated chain creates a soft foam while the carboxylate group keeps it gentle across a wide pH range and helps stabilize oil-in-water mixtures.
While not as famous as sulfates or newer amino acid surfactants, it appears in a fair number of shampoos, face washes and micellar waters where brands want a balance of effective cleansing and mildness.
Current safety data show low irritation potential at typical use levels and minimal absorption through intact skin. Still, everyone’s skin is unique so patch testing any new product that contains this ingredient is a smart precaution.