What Is C11-15 Alketh-40?
C11-15 Alketh-40 is a man-made ingredient created by reacting a blend of synthetic fatty alcohols that have carbon chain lengths of 11 to 15 with about 40 units of ethylene oxide. The result is a polyethylene glycol ether that behaves a lot like a mild detergent and helper solvent in water-based formulas. It first showed up in personal care products in the late 1970s when chemists were looking for gentler alternatives to harsher surfactants. Commercial production starts with lab-manufactured fatty alcohols, which are then purified and fed through a process called ethoxylation where ethylene oxide gas is added under heat and pressure. Careful control of temperature and reaction time lets manufacturers hit the target of roughly 40 ethylene oxide units per alcohol molecule, a sweet spot that balances cleansing power with skin friendliness.
Because it can lift oil and dirt without stripping the skin, C11-15 Alketh-40 is found in a wide range of rinse-off and leave-on items. You will see it in facial cleansers, micellar waters, exfoliating masks, makeup removers, lightweight lotions, hair conditioners, shower gels and even some sunscreens where it helps dissolve oily UV filters into the water phase.
C11-15 Alketh-40’s Cosmetic Benefits/Uses
Formulators reach for C11-15 Alketh-40 because it reliably performs two key jobs in a single ingredient.
- Cleansing: Its surfactant nature loosens dirt, excess sebum and makeup so they can be rinsed away with water, leaving skin or hair feeling fresh but not squeaky-dry.
- Solubilizing: It acts like a tiny matchmaker between oil and water, helping stubborn fragrance oils, essential oils or silicone-based actives disperse evenly in a water-based formula which prevents separation and gives products a clear, uniform appearance.
Who Can Use C11-15 Alketh-40
C11-15 Alketh-40 is generally well tolerated by most skin types. Oily and combination skins appreciate its ability to lift excess sebum without leaving residue, while normal skin benefits from its mild cleansing action. Sensitive or very dry skin can usually handle it in low to moderate concentrations, but formulas with a high percentage of this surfactant might feel a bit tight on already compromised skin because it does remove some surface lipids.
The ingredient is fully synthetic and contains no animal-derived raw materials, so it is suitable for vegans and vegetarians. Manufacturers commonly list it on cruelty-free product labels for this reason.
Current safety data show no specific restrictions for women who are pregnant or breastfeeding when the ingredient is used at typical cosmetic levels. This is not medical advice and anyone who is expecting or nursing should discuss new skincare products with their doctor to be safe.
C11-15 Alketh-40 does not make skin more sensitive to the sun, nor does it interfere with sunscreen actives. It is also fragrance free and nonvolatile, so it will not contribute to inhalation concerns in spray products.
Potential Side Effects/Adverse Reactions
Responses to topical C11-15 Alketh-40 can differ from one person to the next. The points below outline potential side effects, but most people will not experience them when the ingredient is used correctly in a finished product.
- Mild skin irritation – transient redness or a slight stinging sensation, more likely on compromised or very dry skin
- Contact dermatitis – rare allergic response that may present as itching, rash or swelling
- Eye irritation – possible if the product accidentally gets into the eyes, especially in higher-foam cleansers
- Increased dryness – over-cleansing or using multiple surfactant-rich products can strip natural oils and leave skin feeling tight
If any of these reactions occur stop using the product and seek guidance from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1/5. C11-15 Alketh-40 is highly water soluble and designed to rinse away cleanly, so it does not linger on the skin long enough to block pores. Unlike heavier fatty alcohols or oils, its large polyethylene glycol portion keeps it from forming an occlusive film that could trap dead cells or sebum. Because it is most often used at low levels and in products that are washed off, the risk of pore clogging is minimal.
Acne-prone individuals can generally use products containing C11-15 Alketh-40 without added worry of breakouts.
One extra point: if a formula pairs this ingredient with rich plant oils or waxes, the overall product could still feel heavy on congested skin. In those cases judge the full ingredient list rather than this single component.
Summary
C11-15 Alketh-40 is primarily a cleanser and solubilizer. Its surfactant head loosens dirt, oil and makeup so they can be rinsed away while its affinity for both water and oil lets it pull fragrant oils or sunscreen actives into a uniform solution that stays clear and stable.
You will not see it called out on the front label the way you would with buzzy actives, yet it quietly appears in a wide range of cleansers, toners, micellar waters and lightweight lotions because formulators trust its reliability.
Current research and decades of use show it to be low risk for irritation, sensitization or acne when used at normal cosmetic levels. Still, skin is individual. Whenever you try a new product that lists C11-15 Alketh-40 it is smart to do a small patch test first to make sure your skin agrees.