What Is C11-15 Sec-Pareth-12?
C11-15 Sec-Pareth-12 is a group of secondary alcohols that have been reacted with roughly 12 units of ethylene oxide. The numbers 11-15 describe the length of the original fatty alcohol chain, while the “12” points to the average number of ethylene oxide units attached. The end result is a clear to slightly hazy liquid that mixes well with both oil and water.
The base fatty alcohols usually come from plant oils such as coconut or palm, though they can also be sourced from petroleum. Chemists first explored ethoxylated alcohols in the mid-20th century when the growing detergent industry needed safer, milder cleaners for skin and hair. Over time formulators noticed that these ingredients also helped blend oil and water, making them handy in many personal care products.
Manufacturing starts with the purified C11-C15 secondary alcohols. Under carefully controlled heat and pressure, ethylene oxide gas is added step by step until about 12 units have attached to each alcohol molecule. The finished material is then neutralized, filtered and quality-checked before shipment to cosmetic labs.
Because it cleans without stripping and keeps mixtures stable, C11-15 Sec-Pareth-12 shows up in facial cleansers, body washes, shampoos, micellar waters, exfoliating scrubs, liquid hand soaps and some lightweight lotions or sprays where a low-foaming yet effective surfactant is needed.
C11-15 Sec-Pareth-12’s Cosmetic Benefits/Uses
This ingredient pulls double duty in formulas, offering both cleansing power and mix-helping support.
- Cleansing: Lowers the surface tension of water so oils, dirt and makeup can lift away more easily. It creates a mild lather that rinses clean, leaving skin or hair feeling fresh without a tight after-feel.
- Emulsifying: Helps oil and water stay blended, keeping a product smooth and uniform from the first pump to the last use. This prevents separation in lotions, gels or cleansing oils, improving shelf life and user experience.
Who Can Use C11-15 Sec-Pareth-12
C11-15 Sec-Pareth-12 is generally well tolerated by most skin and hair types. Its mild cleansing action means it suits normal, oily, combination and even sensitive skin because it lifts grime without a harsh stripping effect. Those with very dry or compromised skin barriers should still balance it with moisturising ingredients, as any surfactant can contribute to dryness if overused.
The ingredient itself is synthetic or plant derived, with no animal by-products involved, so it is considered suitable for both vegetarians and vegans. If a formula containing it also uses other animal-sourced additives, that will be listed separately on the label.
No specific warnings exist for pregnant or breastfeeding women regarding topical use of C11-15 Sec-Pareth-12. Current safety reviews show it does not penetrate deeply or act hormonally. This is not medical advice, so anyone who is expecting or nursing should still clear any new skincare routine with a healthcare professional to be safe.
The molecule does not make skin more prone to sunburn, so it is not regarded as photosensitising. It is also considered colour-safe for dyed hair and does not interact with common active ingredients such as retinoids or vitamin C.
Potential Side Effects/Adverse Reactions
Responses to topical C11-15 Sec-Pareth-12 can vary between individuals. The points below outline potential side effects yet these outcomes are uncommon when the ingredient is formulated and used as intended.
- Redness or irritation: A small number of users may notice temporary flushing or a tingling sensation, especially if their skin is already sensitive or damaged
- Dryness or tightness: Overuse or leave-on exposure can pull away natural oils leading to a dry afterfeel
- Eye stinging: If a cleanser containing the ingredient gets into the eyes it can cause short-lived discomfort and watering
- Allergic contact dermatitis: Extremely rare but possible for individuals with a specific sensitivity to ethoxylated alcohols
If you experience any persistent discomfort stop using the product and consult a qualified healthcare professional or dermatologist for guidance.
Comedogenic Rating
Rating: 1 / 5
C11-15 Sec-Pareth-12 is a water-soluble surfactant that rinses off cleanly and leaves very little residue on the skin. Because it does not deposit heavy oils or waxes that can block pores, the risk of clogging is considered low, earning it a rating of 1. Mild cleansers in general can feel drying if overused, but dryness alone does not equal comedogenicity.
Given its low rating this ingredient is usually suitable for people who are prone to acne or breakouts.
Most finished formulas use it at modest levels alongside other low-comedogenic ingredients, so its presence rarely shifts the overall pore-clogging potential of a product.
Summary
C11-15 Sec-Pareth-12 acts as both a cleanser and an emulsifier. Its long-chain alcohol backbone grabs onto oils while the attached ethylene oxide units attract water, so it lifts away dirt then washes off easily. The same oil-and-water friendly structure helps keep emulsions stable, preventing separation in lotions or gels.
The ingredient sees steady but not superstar use. It appears most often in gentle facial cleansers, micellar waters and light body washes where a mild low-foam profile is desired. You will spot it less frequently in rich creams or niche treatments.
Regulatory reviews and decades of cosmetic use show it to be safe for topical application with a very low irritation and allergy rate. As with any new skincare product it is wise to perform a quick patch test to make sure your skin agrees before applying it widely.