Po
Polyaminopropyl Biguanide
Polyaminopropyl Biguanide · Polyhexamethylene Biguanide
A preservative (PHMB) that keeps water-based products from spoiling. It works in very small amounts.
What it does
It keeps water-based products from spoiling by breaking open the bacteria and some fungi that would grow in them. It works in very small amounts. It’s there to protect the formula, not to change your skin.
The EU’s ingredient database lists it as a preservative (holds back germs in the product).European Commission, CosIng (© European Union, CC BY 4.0) · uses put in plain words by Drop ↗
The evidence, graded
expert consensusSCCS/1535/14 (adopted 18 June 2014) concluded that PHMB is not safe for consumers as a preservative in all cosmetic products up to 0.3%, nor in spray formulations at that level. With new dermal absorption data, SCCS/1581/16 (adopted 7 April 2017) was of the opinion that its use as a preservative in all cosmetic products up to 0.1% is safe. As no new inhalation data were available, its use in sprayable formulations is not advised.SCCS 2014 · European Commission SCCS (adopted 18 June 2014) ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
PHMB, polyhexanide
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.