Description

Polyaminopropyl Biguanide (polyhexamethylene biguanide hydrochloride) is a chemical compound, a polyhexamethylene polymer connected with hydrocarbon chains.

Chemical name N'-[6-[(N'-methylcarbamimidoyl)amino]hexyl]ethanimidamide

Safety
Despite being an antiseptic used in ophthalmics, it is considered a skin and eye irritant even though a 2017 study found this ingredient to be of no concern when included at the concentrations used in cosmetics.
https://www.cir-safety.org/sites/default/files/admin_8.pdf

What it is used for and where

Cosmetics
Preservative. Any product containing organic, inorganic compounds, water, needs to be preserved from microbial contamination. Preservatives act against the development of harmful microorganisms and against oxidation of the product.
Synonyms: EC number 608-723-9

CAS: 32289-58-0