What Is Potassium C11-15 Alkyl Phosphate?
Potassium C11-15 Alkyl Phosphate is a surfactant made by linking medium-length fatty alcohols (with 11 to 15 carbon atoms) to phosphoric acid, then neutralizing the mixture with potassium hydroxide. The fatty alcohols usually come from plant oils such as coconut or palm, though they can also be made synthetically. Phosphate-based surfactants first appeared in home and personal care products in the 1950s when manufacturers looked for cleansing agents that were effective yet gentle on skin. Today this ingredient is produced on a large scale by reacting the chosen alcohol blend with phosphorus pentoxide or phosphoric acid under controlled heat, followed by potassium neutralization and purification.
In cosmetics you will most often spot Potassium C11-15 Alkyl Phosphate in foaming or rinse-off formulas. Shampoos, facial cleansers, micellar waters, body washes, exfoliating scrubs, bubble baths and some cleansing masks use it to help break up oil and grime so they wash away easily. Because it works well in both low and high pH systems, formulators may also add it to specialty products such as shaving creams and baby washes that need a mild yet effective cleanser.
Potassium C11-15 Alkyl Phosphate’s Cosmetic Benefits/Uses
This ingredient serves one main purpose in skin and hair care products: cleansing. As a surfactant it lowers the surface tension of water, allowing oils, makeup, sweat and environmental debris to mix with the rinse water and leave the skin or hair. Its balanced fatty chain length gives it enough power to remove dirt while staying gentle enough for daily use. It also contributes to a creamy lather and helps other ingredients spread evenly during application, making the overall formula feel more pleasant and rinse off without residue.
Who Can Use Potassium C11-15 Alkyl Phosphate
This surfactant is generally well tolerated by most skin types, including normal, oily, combination and even sensitive skin because it cleans without overly stripping the skin’s natural barrier. Very dry or compromised skin may still want to pair it with richer moisturizers since any cleanser has the potential to remove some surface lipids.
The ingredient is considered suitable for vegans and vegetarians when the fatty alcohols are sourced from plant oils, which is usually the case. Those who avoid animal-derived ingredients can check with the brand to confirm plant sourcing and sustainable harvesting of raw materials such as coconut or palm oil.
No data suggests special risks for women who are pregnant or breastfeeding when this ingredient is used in rinse-off products. Still, this information is not medical advice and anyone who is pregnant or nursing should show their skincare routine to a qualified healthcare provider just to be sure.
Potassium C11-15 Alkyl Phosphate does not make skin more sensitive to sunlight and can be used alongside daytime products without increasing the need for extra sun protection. It is also compatible with most commonly used actives and preservatives, so formulators can include it in a wide range of products without worrying about instability or loss of efficacy.
Potential Side Effects/Adverse Reactions
Side effects from topical use of Potassium C11-15 Alkyl Phosphate vary from person to person. The points below describe potential reactions that could occur, although they are uncommon when the ingredient is correctly formulated and used as directed.
- Mild skin irritation such as redness or a stinging sensation, usually if the formula is left on too long or used too frequently
- Eye stinging or redness if the cleanser accidentally gets into the eyes
- Excessive dryness or tightness particularly on already dehydrated or very dry skin
- Allergic contact dermatitis in rare cases where the user is sensitive to phosphate esters or any impurities in the raw material
- Scalp or hair cuticle roughness if a shampoo containing high concentrations is not followed by a conditioner
If you experience any of the reactions listed above stop using the product and seek guidance from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 0 / 5
Potassium C11-15 Alkyl Phosphate is a water-soluble cleansing agent that does not leave an oily film on skin and is typically rinsed off within seconds, so it has almost no chance to clog pores. For that reason formulators and dermatologists consider it non-comedogenic.
Because of this low rating it is generally suitable for people who are prone to acne or breakouts.
One extra point worth noting is that the ingredient is usually used at low concentrations in finished products, which further minimizes any pore-clogging risk.
Summary
Potassium C11-15 Alkyl Phosphate is mainly a surfactant that lifts away oil, dirt and product buildup by lowering the surface tension of water, letting grime mix with rinse water and wash off cleanly. Its medium-length fatty chains balance cleansing power with gentleness, and it also boosts lather and spreadability so products feel pleasant during use.
While not the most famous ingredient on store shelves, it has a steady following among formulators who want a dependable, mild cleanser that works in many pH ranges. You will spot it most often in shampoos, face washes and micellar waters rather than in leave-on skincare.
Current safety data shows a low risk of irritation or sensitization when used as directed, especially in rinse-off products. Still, everyone’s skin is different, so it is wise to patch test any new product containing Potassium C11-15 Alkyl Phosphate before adding it to your daily routine.