Sodium C9-11 Alketh-6 Carboxylate: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 30, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Sodium C9-11 Alketh-6 Carboxylate?

Sodium C9-11 Alketh-6 Carboxylate is a synthetic cleansing agent made by reacting fatty alcohols that have 9 to 11 carbon atoms with ethylene oxide, then converting the result into a carboxylic acid and neutralizing it with sodium. The finished ingredient is a sodium salt that mixes easily with water and helps oils wash away. It first appeared in personal care formulas in the late twentieth century when chemists were looking for milder alternatives to traditional soaps.

The fatty alcohols used can come from plant sources such as coconut or palm oil, though once they are processed the final material is fully lab made. Production takes place in stages inside large stainless steel reactors where temperature and pressure are carefully controlled to ensure the right chain length and an average of six ethylene oxide units per molecule.

You will most often see Sodium C9-11 Alketh-6 Carboxylate in face washes, body washes, shampoo, bubble baths, micellar waters and occasionally in makeup removers or exfoliating masks. Formulators like it because it works in both hard and soft water, creates a gentle lather and rinses clean without leaving a tight feeling on skin.

Sodium C9-11 Alketh-6 Carboxylate’s Cosmetic Benefits/Uses

The main role of Sodium C9-11 Alketh-6 Carboxylate in cosmetics is cleansing. It lowers the surface tension of water so oils, sweat and everyday grime can lift off the skin or hair and be rinsed away. Because it is milder than many classic sulfates it helps formulas clean effectively while keeping the chance of dryness or irritation low.

Who Can Use Sodium C9-11 Alketh-6 Carboxylate

This cleanser is generally considered safe for all skin types including oily, combination, normal and even many sensitive skins because it is milder than strong sulfate surfactants. Very dry or highly reactive skin could still find any foaming agent a bit dehydrating if used too often so a follow-up moisturizer is wise.

The ingredient is made from plant-derived fatty alcohols and synthetic processing steps with no animal-sourced materials so it is suitable for vegans and vegetarians.

Pregnant or breastfeeding women can usually use products that contain Sodium C9-11 Alketh-6 Carboxylate as the ingredient stays on the surface of skin and is rinsed away. This is not medical advice and anyone who is pregnant or nursing should show their full routine to a qualified doctor to be certain it is right for them.

The molecule does not increase sun sensitivity so there is no special need to avoid daylight beyond normal sunscreen habits.

It blends well with most common cosmetic ingredients and does not carry fragrance on its own so there are no unusual compatibility issues to note.

Potential Side Effects/Adverse Reactions

Reactions to Sodium C9-11 Alketh-6 Carboxylate differ from person to person. The following are potential side effects that could occur even though most users will not notice any problems when the ingredient is used in a well-formulated product.

  • Mild skin dryness – can appear if the cleanser is left on too long or used many times a day
  • Tight or squeaky feeling – more common on very dry or mature skin that already lacks natural oils
  • Transient redness or stinging – usually linked to over-scrubbing or underlying sensitivity
  • Eye irritation – possible if the wash gets into the eyes during rinsing
  • Rare allergic contact dermatitis – presents as itching rash or swelling in those who are specifically allergic to this class of ingredients

If any irritation develops stop using the product and seek guidance from a healthcare professional.

Comedogenic Rating

Rating: 0/5 – Sodium C9-11 Alketh-6 Carboxylate is a water-soluble surfactant that fully rinses away, leaving virtually no film that could block pores. It does not contain heavy oils or waxes and is used at low concentrations, so the chance of it trapping debris inside follicles is extremely slim. This makes the ingredient suitable for acne-prone or breakout-prone skin.

Because it is washed off and often paired with other mild surfactants, any residue that remains is negligible. Only in unusually high leave-on levels would pore blockage become a realistic concern, and that use pattern is not typical for this ingredient.

Summary

Sodium C9-11 Alketh-6 Carboxylate is primarily a cleansing agent that lifts oils, sweat and dirt by lowering water’s surface tension and forming micelles that trap grime. Its mild nature lets formulators create gentle face washes, shampoos and body washes that foam well yet rinse clean without stripping skin.

The ingredient is moderately popular, seen more often in niche or sensitive-skin formulas than in mass-market products dominated by sulfates. Chemists appreciate its balance of efficacy and gentleness, though its higher cost compared to traditional detergents keeps it from appearing in every shelf staple.

Overall safety is high since it stays on the surface and is removed with water, with irritation risks limited mainly to overuse on already dry or sensitive skin. As with any new skincare product, patch testing is a smart precaution before full use.

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