Diammonium dithiodiglycolate finds its primary application in the field of hair care and cosmetic products. It is commonly used as a reducing agent in hair straightening and perming formulations. The compound works by breaking the disulfide bonds in keratin, the protein structure of hair, allowing the hair to be reshaped into a new configuration. Once the hair is set in the desired style, an oxidizing agent is applied to reform the disulfide bonds, locking the new shape in place. This makes it a key ingredient in professional hair treatments aimed at achieving smooth, straight hair or defined curls. Additionally, it is valued for its relatively gentle action compared to other chemical straightening agents, reducing the risk of hair damage when used correctly. Its effectiveness and safety profile have made it a popular choice in salon-grade and at-home hair care products.