Hydrogen Peroxide is a clear, colorless liquid. In cosmetics and personal care products, Hydrogen Peroxide can be found in a wide variety of hair care products such as hair dyes, hair bleaches, conditioners, shampoos and rinses, hair bleaches and shampoos. It is also used in tooth whitening products. Hydrogen Peroxide is also sold as an antiseptic at concentrations of 2.5-3%. The Food and Drug Administration (FDA) includes Hydrogen Peroxide in its list of substances affirmed Generally Recognized As Safe (GRAS) for use in food. Hydrogen peroxide is used as an antimicrobial agent, an oxidizing and reducing agent, and bleaching agent in foods such as milk and cheese products, wine, vinegar, starch and instant tea. The FDA also allows Hydrogen Peroxide to be used in Over-the-Counter (OTC) first aid antiseptics. Hydrogen Peroxide is added to cosmetics and personal care products as an antimicrobial agent and as an oxidizing agent. The function of antimicrobial agents is to kill or inhibit the growth or reproduction of microorganisms. In cosmetics and personal care products, oxidizing agents are used to form dyestuffs during oxidative hair dyeing, and to oxygenate stains on the teeth to further whiten the teeth.

Source: Dweck, Anthony. Handbook of Cosmetic Ingredients: - their use, safety and toxicology (Dweck Books 5)