What Is C12-15 Alketh-9 Phosphate?
C12-15 Alketh-9 Phosphate is a surfactant created by reacting fatty alcohols that contain 12 to 15 carbon atoms with ethylene oxide, then further treating the resulting C12-15 Alketh-9 with phosphoric acid to form a phosphate ester. The outcome is a versatile liquid or paste that mixes comfortably with both water and oil, a trait that makes it valuable in modern skincare and haircare formulas.
The fatty alcohols used to make this ingredient are typically sourced from coconut or palm kernel oils, giving the material a plant derived backbone. Ethoxylation, the process of adding ethylene oxide, increases the molecule’s water-loving character. Phosphorylation then adds an acidic group that helps stabilize emulsions. These manufacturing steps have been refined since the 1970s, when formulators were searching for gentle yet efficient alternatives to older, harsher surfactants. As regulations and consumer expectations for mildness grew, C12-15 Alketh-9 Phosphate found a steady place on ingredient lists.
You will commonly spot this phosphate ester in lightweight facial moisturizers, creamy body lotions, rinse-off cleansers, conditioning shampoos, sunscreens, makeup removers and leave-on hair treatments. Whenever a product claims to have a smooth texture that spreads easily without separating, an emulsifier like C12-15 Alketh-9 Phosphate is often helping behind the scenes.
C12-15 Alketh-9 Phosphate’s Cosmetic Benefits/Uses
This ingredient serves one main purpose in cosmetics and personal care products, yet that single role has multiple payoffs for both the formula and the user.
Emulsifying: C12-15 Alketh-9 Phosphate helps oil and water blend into a stable, uniform mixture. A well-built emulsion keeps a lotion from splitting, ensures even distribution of active ingredients and delivers a pleasant, non greasy feel on skin or hair. By maintaining consistency throughout a product’s shelf life it also improves the overall performance and sensory appeal of creams, milks and sprays.
Who Can Use C12-15 Alketh-9 Phosphate
Most skin types can use products that contain C12-15 Alketh-9 Phosphate. It is gentle enough for normal, dry, oily and combination skin thanks to its mild surfactant profile. People with very sensitive or compromised skin usually tolerate it as well, though they may still prefer formulas that pair it with soothing ingredients.
This material is made from plant based fatty alcohols and does not rely on animal by-products, so it is suitable for vegans and vegetarians. The ethoxylation step uses synthetic ethylene oxide rather than anything animal derived, keeping the final ingredient free of animal input.
Based on the way it stays on the surface of skin and the low levels typically used, C12-15 Alketh-9 Phosphate is not expected to pose a special risk for women who are pregnant or breastfeeding. That said, this is not medical advice and anyone who is expecting or nursing should ask a healthcare professional before starting any new skincare product just to be sure.
The ingredient does not cause photosensitivity, so it will not make skin more prone to sunburn. It also plays well with common actives such as retinol, vitamin C and exfoliating acids without impacting their performance.
Potential Side Effects/Adverse Reactions
Reactions to the topical use of C12-15 Alketh-9 Phosphate differ from person to person. The points below describe potential side effects, but most people will not experience them when the ingredient is used at the low levels found in finished products.
- Mild skin irritation – in rare cases a formula that is heavily loaded with surfactants may leave skin feeling tight or slightly itchy
- Redness or stinging on very sensitive skin – those with conditions like eczema could notice temporary warmth or tingling
- Eye irritation – if a product accidentally gets into the eyes it may cause watering or a brief burning sensation
- Contact allergy – extremely uncommon but possible for a small group of users who may develop a rash or bumps
If any discomfort, redness or swelling appears while using a product that contains C12-15 Alketh-9 Phosphate, stop using it and consult a healthcare professional if the reaction does not settle quickly.
Comedogenic Rating
Rating: 1 / 5
C12-15 Alketh-9 Phosphate is a water loving surfactant that tends to sit on the surface and rinse away rather than clog pores. It is used at low levels, is not an oil in the traditional sense and does not leave a heavy residue. Because of these traits the chance of it trapping sebum or dead skin inside the follicle is very slim, which is why it earns a low score of 1.
This makes the ingredient generally suitable for people who are prone to acne or breakouts.
As with any single rating, the overall formula still matters. A product packed with rich plant butters or waxes may feel heavier on the skin even if this phosphate ester itself is non-pore-clogging.
Summary
C12-15 Alketh-9 Phosphate is an emulsifier that lets water and oil coexist so creams stay smooth and actives spread evenly. It achieves this by carrying both a fatty alcohol tail and a phosphate head, giving it the dual nature needed to stabilize emulsions and improve skin feel.
While not as famous as ingredients like glycerin or hyaluronic acid, it is a quiet workhorse that shows up in a wide range of cleansers, lotions and hair products because it is reliable, plant derived and mild.
Current safety data show it is well tolerated by most skin types with only rare irritation or allergy reports. Still, skin is personal so it is wise to patch test any new product that lists C12-15 Alketh-9 Phosphate to make sure it plays nicely with your own complexion.