1-Butylhydantoin is primarily used in the personal care and cosmetics industry as a conditioning agent. It helps to improve the texture and manageability of hair, making it a common ingredient in shampoos, conditioners, and other hair care products. Additionally, it is utilized in skincare formulations for its moisturizing properties, helping to maintain skin hydration and smoothness. Its mild nature makes it suitable for sensitive skin types, contributing to its widespread use in various cosmetic applications.