What Is Potassium C9-15 Alkyl Phosphate?
Potassium C9-15 Alkyl Phosphate is the potassium salt formed when a mix of synthetic alcohols, each with 9 to 15 carbon atoms, is reacted with phosphoric acid. The result is a group of mild surfactant molecules that carry both water-loving and oil-loving parts, letting them interact with dirt and oils on the skin.
The ingredient grew popular in the 1990s as brands searched for sulfate-free cleaning agents that felt gentle yet still created a satisfying lather. By swapping sulfates for phosphate-based surfactants chemists found they could lower the risk of irritation while keeping cleansing power.
Production starts with lab-made fatty alcohols. These alcohols are esterified with phosphoric acid, then neutralized with potassium hydroxide. Careful control of temperature and pH produces a clear liquid or paste that blends easily into water-based formulas.
You’ll spot Potassium C9-15 Alkyl Phosphate in face cleansers, body washes, micellar waters, exfoliating pads, makeup-removing wipes and even some shampoo alternatives. Because it is mild it also appears in rinse-off masks and baby cleansing products where skin comfort is key.
Potassium C9-15 Alkyl Phosphate’s Cosmetic Benefits/Uses
In skin and hair care this ingredient serves one main purpose that benefits both the formula and the user.
Cleansing: As a surfactant it lowers the surface tension of water so oils, makeup and everyday grime can be lifted away and rinsed off. It produces a soft foam, spreads easily and leaves skin feeling refreshed rather than stripped, making it ideal for gentle daily cleansers.
Who Can Use Potassium C9-15 Alkyl Phosphate
Thanks to its gentle nature this surfactant suits nearly every skin type including normal, dry, oily and combination skin. People with easily irritated or sensitized skin often tolerate it better than stronger sulfate cleansers but anyone with a known allergy to phosphate-based surfactants should steer clear.
The ingredient is made from laboratory-produced fatty alcohols and mineral-derived phosphoric acid so it contains no animal material and is therefore suitable for vegans and vegetarians.
No studies have linked topical use of Potassium C9-15 Alkyl Phosphate to problems during pregnancy or while breastfeeding. Still this is not medical advice and anyone who is pregnant or nursing should show the full product label to a doctor before adding it to a routine.
Unlike ingredients that increase sun sensitivity this phosphate surfactant does not make skin more prone to UV damage. Standard daytime sunscreen habits are all that is needed.
Because it is used in rinse-off formulas it rarely stays on the skin long enough to interact with leave-on actives, fragrances or makeup though a well-formulated product will account for overall pH balance to avoid unnecessary dryness.
Potential Side Effects/Adverse Reactions
Reactions to Potassium C9-15 Alkyl Phosphate differ from person to person. The points below list potential side effects which remain uncommon when the ingredient is properly formulated and used as directed.
- Mild transient stinging a short-lived tingle that may occur on freshly shaved or compromised skin
- Redness or irritation usually linked to high use levels or prolonged contact time
- Dry or tight feeling if the cleanser is left on too long or not followed by moisturizer
- Allergic contact dermatitis rare but possible in people sensitive to phosphate esters
- Eye irritation tearing or mild burning if the formula accidentally gets into the eyes
If discomfort or any of the above effects develop stop using the product and seek guidance from a healthcare professional.
Comedogenic Rating
Rating: 0 / 5
Potassium C9-15 Alkyl Phosphate is a water-soluble cleansing agent that rinses off fully and does not leave an oily film behind. Because it has no fatty residues that can build up inside pores its potential to clog follicles is practically nil. Most safety and formulation data place phosphate surfactants at the very bottom of comedogenic charts.
Suitable for those prone to acne or breakouts.
Its quick rinse-off nature means it spends little time on the skin further lowering any chance of pore blockage.
Summary
Potassium C9-15 Alkyl Phosphate is mainly a mild surfactant that lifts oils dirt and makeup by lowering the surface tension of water then washes clean without stripping skin. It creates a gentle foam and keeps formulas clear and stable.
The ingredient saw a rise in use when brands began moving away from sulfates in the 1990s and it remains a steady favorite in gentle cleansers micellar waters and baby washes though it is less talked about than newer trendy surfactants.
Overall it is considered safe for most users with a low risk of irritation or pore blockage. As with any new skincare product it is wise to patch test first to be sure your skin agrees with the full formula.