1-(diaminomethylidene)-2-hexylguanidine

Polyhexanide (polyhexamethylene biguanide, PHMB) is a polymer used as a disinfectant and antiseptic. In dermatological use, it is spelled polihexanide (INN) and sold under names such as Lavasept, Serasept, and Omnicide. PHMB has been shown to be effective against Pseudomonas aeruginosa, Staphylococcus aureus (also the methicillin-resistant type, MRSA), Escherichia coli, Candida albicans (yeast), Aspergillus brasiliensis (mold), vancomycin-resistant enterococci, and Klebsiella pneumoniae (carbapenem-resistant enterobacteriaceae).
Some products containing PHMB are used for inter-operative irrigation, pre- and post-surgery skin and mucous membrane disinfection, post-operative dressings, surgical and non-surgical wound dressings, surgical bath/hydrotherapy, chronic wounds like diabetic foot ulcer and burn wound management, routine antisepsis during minor incisions, catheterization, scopy, first aid, surface disinfection, and linen disinfection. PHMB eye drops have been used as a treatment for eyes affected by Acanthamoeba keratitis.
Branded as Baquacil, it also has an application as a swimming-pool and spa water sanitizer in place of chlorine- or bromine-based products. It is available as Baqua-Spa 3 sanitize, as Revacil Spa 3 sanitizer, and in the Leisure Time Free system.
PHMB is also used as an ingredient in some contact lens cleaning products, cosmetics, personal deodorants and some veterinary products.
The PHMB hydrochloride salt (solution) is used in the majority of formulations.