Polyaminopropyl biguanide (PAPB) is a synthetic polymer that functions as a disinfectant and preservative. It is bactericidal at low concentrations and also fungicidal. It is used in cleaning solutions for contact lenses, deodorant body sprays, and a variety of cosmetics and skin care products. It is also sold on its own to be applied directly to the skin and even wounds. Polyaminopropyl biguanide has a unique method of action: its polymer strands are incorporated into the bacterial cell membrane, which disrupts the membrane and reduces its permeability, which ultimately destroys the bacteria.

Preservatives like polyaminopropyl biguanide are used in the formulation of cosmetics and personal care products in order to extend the shelf-life by preventing microbial contamination. The use of preservatives in cosmetics is important because these types of products have a high potential for microbial contamination and growth. The most susceptible products are creams and lotions that are packaged in jars, opened frequently, and applied to the skin with the fingers. Microbial contamination can lead to significant health problems, from skin irritation to infections. To avoid these problems, a preservative should be added to the formulation.