Ingredient review

Polyquaternium-38

INCI: Polyquaternium-38

A gentle conditioning polymer that smooths hair and adds slip without heavy buildup, but may not suit very fine or low-porosity hair if used in high amounts.

beautyskincarehaircareconditioning agent

In plain English

Polyquaternium-38 is a synthetic, positively charged polymer that sticks to the negatively charged surface of hair and skin. This cling helps reduce static electricity, smooths the hair cuticle, and makes strands feel softer and easier to comb. In skincare, it can create a light, silky film that improves the feel of a product without being greasy. Think of it as a very mild, temporary coating that helps everything glide on and feel nicer.

Review score

Safety, usefulness, and evidence

3.8Good

3.8/ 5

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

How reviews are scored

Quick decision guide

Useful, but context matters

Polyquaternium-38 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-38.
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

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

A cationic (positively charged) polymer belonging to the polyquaternium family, specifically designed to deposit onto hair and skin from rinse-off or leave-on formulas.

How it works

Its positive charge attracts it to the negative charges on damaged hair and skin. Once deposited, it forms a thin, flexible film that smooths the surface, reduces friction, and helps prevent flyaways. This film also helps other conditioning ingredients stay put.

Pros

Gentle conditioning

Provides noticeable slip and softness without the heavy, greasy feel of some oils or silicones, making it suitable for daily use.

Static control

Effectively reduces flyaways and static electricity, especially in dry or winter conditions, helping hair stay smooth and tidy.

Cons and cautions

Potential buildup

On very fine or low-porosity hair, repeated use without clarifying shampoo can lead to a slight film that may dull shine or weigh hair down.

Synthetic origin

As a synthetic polymer, it may not appeal to consumers seeking exclusively natural or biodegradable ingredients.

Best for

Anyone looking for a gentle, non-greasy conditioner for normal to dry hair
People who want to reduce static and improve manageability without heavy silicones

Use caution if

Those with very fine or easily weighed-down hair who prefer lightweight, protein-free conditioners (though PQ-38 is generally lighter than many alternatives)

Usage tips

Use in rinse-off conditioners or leave-in sprays at low concentrations (0.1–1%) for best results without buildup.

Pair with a gentle clarifying shampoo once a week if you have fine hair and use multiple conditioning products.

Avoid combining with high concentrations of anionic surfactants (like SLS) in the same formula, as they can reduce its effectiveness.

Safety summary

Polyquaternium-38 has a low irritation and comedogenic risk. It is well-tolerated by most skin and scalp types. No significant safety concerns have been identified at typical cosmetic use levels.

Research notes

Research on polyquaternium-38 is limited compared to more common polyquaterniums (e.g., PQ-7, PQ-10). Available data from the CIR and manufacturer studies indicate it is a safe, effective conditioning agent with low irritation potential.

Common label clues

Typical concentration: 0.1% to 2%
Regulatory status: Approved for use in cosmetics in the US, EU, and many other regions. The Cosmetic Ingredient Review (CIR) panel has deemed it safe as used in rinse-off and leave-on products.
Common uses: Conditioners, Leave-in treatments, Shampoos, Styling products, Body washes
Environmental note: As a synthetic polymer, its biodegradability is limited. Some polyquaterniums can persist in aquatic environments, though PQ-38 is generally considered less concerning than older, larger polymers.

Good to know

Polyquaternium-38 is often used in combination with other polyquaterniums to fine-tune conditioning and film-forming properties.
It is considered safe for use in cosmetics by the Cosmetic Ingredient Review (CIR) panel at typical use levels.

Common questions

What is Polyquaternium-38 in beauty products?

What does Polyquaternium-38 do in a beauty product?

Is Polyquaternium-38 safe for most people?

Polyquaternium-38 has a low irritation and comedogenic risk. It is well-tolerated by most skin and scalp types. No significant safety concerns have been identified at typical cosmetic use levels.

Who should be careful with Polyquaternium-38?

Those with very fine or easily weighed-down hair who prefer lightweight, protein-free conditioners (though PQ-38 is generally lighter than many alternatives)

Research sources

Cosmetic Ingredient Review (CIR) – Safety Assessment of PolyquaterniumsOpen PubChem – Polyquaternium-38Open Personal Care Council – Polyquaternium-38Open

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.