What Is Polyquaternium-90?
Polyquaternium-90 is a man-made ingredient classified as a polymeric quaternary ammonium salt. It is created by linking together acrylamide and hydroxyethylcellulose, then quaternizing that chain with diallyldimethyl ammonium chloride. The quaternization step gives the molecule a positive charge, which is the key to its performance on hair and skin surfaces. Developed in the late 20th century during the search for better styling and conditioning agents, Polyquaternium-90 quickly found favor for its ability to form clear flexible films without a sticky feel.
The manufacturing process starts with water-based polymerization of acrylamide and hydroxyethylcellulose. Once the desired chain length is reached, chemists introduce diallyldimethyl ammonium chloride under controlled temperature and pH, converting the neutral polymer into a cationic one. After purification and concentration, the final product is usually supplied as an easy-to-handle aqueous solution.
You will most often see Polyquaternium-90 in leave-in or rinse-off hair products such as gels, mousses, sprays, conditioners and shampoos. It also shows up in styling creams, edge tamers, temporary color rinses, face masks and some light moisturizers where a smooth protective film is desirable.
Polyquaternium-90’s Cosmetic Benefits/Uses
Formulators turn to Polyquaternium-90 because it delivers several useful actions at once:
- Antistatic: The positive charge neutralizes static electricity that builds up on hair strands, helping prevent flyaways and frizz especially in dry weather.
- Film forming: It lays down a thin uniform coating that locks in moisture, adds a soft touch and enhances shine without weighing hair down.
- Hair conditioning: The cationic film smooths the cuticle, improving combability, reducing breakage and giving hair a healthier look.
- Hair fixing: By creating flexible bonds between strands, it provides light to medium hold in styling products so styles stay in place while retaining movement.
Who Can Use Polyquaternium-90
Because it is water soluble and lightweight, Polyquaternium-90 is generally suitable for all skin and hair types including oily, dry, sensitive and combination. Its gentle film helps hair and skin retain moisture without clogging pores so most people tolerate it well. Those with extremely sensitive or allergy-prone skin should still keep an eye on how their skin responds since any cationic polymer can occasionally cause irritation.
The ingredient is synthesized from petrochemical and plant-derived building blocks with no animal inputs, making it acceptable for both vegans and vegetarians. Manufacturing does not rely on animal testing in regions that recognize alternative safety assessments, yet final product policies vary so consumers who strictly avoid animal testing should check the brand’s stance.
Current safety data show no specific risks for people who are pregnant or breastfeeding when Polyquaternium-90 is used in rinse-off or leave-on cosmetics at typical levels. This is not medical advice; anyone who is pregnant or nursing should discuss any new personal care product with a qualified healthcare provider to be extra certain.
Polyquaternium-90 does not absorb light in the UV range so it does not increase photosensitivity. It can, however, enhance the feel and spread of sunscreens by forming a smooth base layer, which some formulators see as an extra perk.
Potential Side Effects/Adverse Reactions
Side effects from topical use of Polyquaternium-90 differ from person to person. The points below list potential reactions, yet most users experience none of these problems when the ingredient is formulated and used properly.
- Mild skin or scalp irritation – rare tingling or redness, usually in very sensitive individuals or when used at high concentrations
- Contact allergy – uncommon allergic dermatitis presenting as itching or small bumps, more likely in people already allergic to quaternary ammonium compounds
- – a heavy feel or dull film on hair if multiple styling products containing the polymer are layered without adequate cleansing
- Eye stinging – temporary discomfort if a styling spray accidentally gets into the eyes
If any persistent irritation or other adverse effect occurs stop using the product and seek advice from a medical professional.
Comedogenic Rating
Rating: 0 / 5
Polyquaternium-90 is a large water-soluble polymer that sits on the surface of skin and rinses away easily. It contains no oily or waxy components that can seep into pores or harden inside follicles, so it is considered non-comedogenic. Laboratory data and consumer use reports show no link between this ingredient and the formation of whiteheads or blackheads.
Because it scores a zero, Polyquaternium-90 is generally suitable for people who are prone to acne or breakouts.
The only time buildup could mimic clogged pores is if several heavy styling or leave-on products are layered without proper cleansing, though this is a rarity and relates more to overall product load than to Polyquaternium-90 itself.
Summary
Polyquaternium-90 serves as an antistatic, film former, hair conditioner and light hair fixer. Its positive charge lets it bind to negatively charged hair and skin surfaces, forming a clear flexible film that smooths cuticles, tames flyaways, locks in moisture and delivers soft hold without stickiness.
While not as famous as silicones or proteins, this polymer has carved out a steady role in gels, mousses, sprays and a growing number of skin masks because formulators appreciate its balance of performance and ease of use.
Current safety reviews classify Polyquaternium-90 as low-risk for irritation or sensitization when used at normal cosmetic levels. Still, skin is personal so it is wise to patch test any new product that contains it to make sure it agrees with you.