What does a polyquaternium do?

It carries fixed positive charges along a long chain, so it binds to the negatively charged surface of skin and hair and stays after rinsing. The result is less friction and a smoother feel.

Not in the sense of adding or holding water in the skin. It leaves a film that lowers friction and slows evaporation a little; feeling smoother is not the same as being better hydrated.

Should acrylamide in the name worry me?

The polymer is not the monomer. Residual unreacted monomer is a real specification question, limited by rules that each market sets and revises, and it is controlled by the supplier rather than visible on a label.

On hair, repeated washes can leave a cumulative film that a stronger anionic shampoo removes. On skin it matters much less, because skin is exfoliating itself continuously.

Is it safe during pregnancy?

We have left this unknown rather than guess. It is a rinse-off polymer rather than an active, but a pregnancy question about a specific product belongs with a clinician.

Polyquaternium-7 — Ingredient Guide

How it works

Polyquaternium-7 is a synthetic copolymer of acrylamide and a small quaternary ammonium monomer, which gives one long chain carrying many fixed positive charges. Skin and hair surfaces are net negative at ordinary pH, so the polymer is drawn to them, and because it makes so many points of contact along its length it does not come away easily when the water arrives.

That is the whole mechanism, and it is the clearest everyday demonstration of substantivity: a product that is rinsed away deliberately leaving something behind. What stays is a thin, flexible film that lowers friction, so hair detangles and skin feels smooth and slightly coated rather than squeaky. It also softens the surfactants it travels with, which is a second reason it is in the bottle.

The evidence

The deposition is real, measurable and the reason the material exists. What it is evidence of needs care. A smooth after-feel is a change to the surface, not to the barrier: nothing has been repaired, no lipid replaced, no water content raised beyond what a film slows down. A cleanser that leaves skin feeling looked after may be doing exactly that and no more, which is fine until it is credited with more.

The manufacturing question worth knowing is residual monomer. Acrylamide is a monomer of concern, and a polymer built from it is supplied against a specification limiting how much unreacted monomer may remain. That limit is set by each market and revised, so the current local rule is the reference. It is a supplier and regulator matter rather than something a label reveals, and no figure is quoted here.

Suitability

No skin type needs it; it changes how a wash feels rather than what it does
Anyone who wants a squeaky finish will not want it
Skin that finds cleansers tightening often prefers products that carry it
Found in body washes, facial cleansers, micellar waters and shampoos

Concentration

Used at a low level and not disclosed. Polymers of this kind work at fractions of a percent, which also places them below the point at which an ingredient list has to keep its order, so the position of the name says nothing about the amount. What can be judged is the result: if a wash leaves skin feeling coated, something is depositing.

Conflicts & combinations

Being cationic it is the classic partner for an anionic cleansing system — but as a designed pairing, since the two charges can also form an insoluble complex when the ratio is wrong. That is a formulation problem rather than a routine one. On skin there is nothing to schedule around it; on hair the film is cumulative over repeated washes and comes off with a stronger, more anionic wash, which is what a clarifying step is for.