Cited skincare — every flag names its source, no upsell.
Po

Polyquaternium-11

Polyquaternium-11

A hair-product polymer that forms a film and cuts static.

What it does

It’s a polymer with a positive charge. The EU lists it to form a film and to reduce static.

The evidence, graded

expert consensusUS safety reviewers’ 1983 report describes polyquaternium-11 as a polymer used in hair products at up to 50%. In repeated patch tests on people at up to 50% it caused no allergy and only rare, passing irritation, and the reviewers judged it safe as used. In 2023 they looked again, when leave-on products used it at up to 2.9%, and kept that verdict.Cosmetic 1983 · Journal of the American College of Toxicology 2(5):161-178 (CIR portal copy) ↗

Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.

Browse all 1238 ingredients — grouped by what they do, each with whatever evidence we can cite.

This page is public so a shared ingredient card always has its sources behind it — and so you can check them without an account.
Want more like this?
Every evidence-based flag cites its source, Drop tells you when your routine is complete, and it helps you simplify — instead of selling you more. The app launches on iOS and Android in October 2026. Rate my routine works today at /rate — no sign-in.