Ingredient review
Polyquaternium-90
INCI: Polyquaternium-90
A gentle, effective conditioning polymer that smooths hair without heavy buildup.
In plain English
Polyquaternium-90 is a positively charged polymer that sticks to the negatively charged surface of hair. This helps it form a thin, flexible film that smooths the hair cuticle, reduces static and frizz, and makes hair feel softer and easier to comb. It is often used in rinse-off and leave-on hair products because it provides conditioning benefits without leaving hair feeling greasy or weighed down.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Polyquaternium-90 is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Polyquaternium-90.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
Polyquaternium-90 is a synthetic, water-soluble polymer belonging to the polyquaternium family. It is designed to deposit onto hair and skin to provide conditioning, detangling, and antistatic properties.
How it works
When applied, the positive charge of Polyquaternium-90 binds to the negative charges on hair and skin surfaces. This creates a thin, even film that smooths the hair cuticle, reduces friction, and helps prevent flyaways. The film also helps lock in moisture and can improve the feel of the product during application.
Pros
Lightweight conditioning
Provides noticeable smoothness and detangling without the heavy, greasy feel of some oils or silicones, making it ideal for fine or normal hair.
Frizz control
Helps seal the hair cuticle, reducing humidity-induced frizz and flyaways for a sleeker appearance.
Cons and cautions
Potential buildup
With repeated use, especially without clarifying shampoos, it can accumulate on hair, leading to dullness or limpness over time.
Synthetic origin
As a synthetic polymer, it may not appeal to those seeking fully natural or biodegradable ingredient lists.
Best for
- People with dry, frizzy, or damaged hair
- Those looking for a lightweight conditioner for fine hair
Use caution if
- People with very oily hair who prefer minimal conditioning
- Those with known sensitivity to quaternary ammonium compounds
Usage tips
Safety summary
Polyquaternium-90 has a low irritation and comedogenic risk. It is considered safe for most skin and hair types when used in typical cosmetic concentrations. No significant safety concerns have been reported in regulatory reviews.
Research notes
Studies on polyquaternium compounds generally support their safety and efficacy as conditioning agents. Specific research on Polyquaternium-90 is limited, but it is structurally similar to other well-studied polyquaterniums with a strong safety profile.
Common label clues
- Typical concentration
- 0.1% to 2%
- Regulatory status
- Approved for use in cosmetics in the EU, US, and other major markets. Generally recognized as safe when used as directed.
- Common uses
- Conditioners, Leave-in treatments, Styling products, Shampoos
- Environmental note
- Polyquaternium-90 is not readily biodegradable in all environments, but its low concentration in rinse-off products limits environmental impact.
Good to know
- Polyquaternium-90 is often used in 'low-poo' or sulfate-free shampoos to compensate for reduced cleansing power.
- It is considered safe for color-treated hair as it does not strip dye.
Common questions
What is Polyquaternium-90 in beauty products?
Polyquaternium-90 is a positively charged polymer that sticks to the negatively charged surface of hair. This helps it form a thin, flexible film that smooths the hair cuticle, reduces static and frizz, and makes hair feel softer and easier to comb. It is often used in rinse-off and leave-on hair products because it provides conditioning benefits without leaving hair feeling greasy or weighed down.
What does Polyquaternium-90 do in a beauty product?
When applied, the positive charge of Polyquaternium-90 binds to the negative charges on hair and skin surfaces. This creates a thin, even film that smooths the hair cuticle, reduces friction, and helps prevent flyaways. The film also helps lock in moisture and can improve the feel of the product during application.
Is Polyquaternium-90 safe for most people?
Polyquaternium-90 has a low irritation and comedogenic risk. It is considered safe for most skin and hair types when used in typical cosmetic concentrations. No significant safety concerns have been reported in regulatory reviews.
Who should be careful with Polyquaternium-90?
People with very oily hair who prefer minimal conditioning Those with known sensitivity to quaternary ammonium compounds
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.