Thioglycolic Acid

Thioglycolic acid is an organic compound containing a thiol group (a sulphur-containing functional group). It is a reducing agent, meaning it can break chemical bonds in proteins, particularly the disulphide bonds that give hair its structure and strength.In cosmetic formulations, thioglycolic acid is primarily used in hair removal products and hair-straightening or waving treatments. It works by chemically altering the protein structure of hair, allowing it to be removed or reshaped. The ingredient is also listed as an antioxidant in some formulations, though this is not its primary cosmet…

Thioglycolic acid works by reducing disulphide bonds (S–S) in the keratin protein that makes up the hair shaft. These bonds give hair its shape and strength. By breaking them down, the ingredient allows the hair structure to become more malleable or to be more easily removed from the follicle.In depilatory products, the weakened hair is then washed away. In permanent waving or straightening treatments, the hair is reshaped whilst the bonds are broken, then reformed (set) using an oxidising agent to create new disulphide bonds in the desired configuration.

Thioglycolic acid products (such as hair removal creams or permanent wave solutions) should be used according to product instructions, as timing and application method are critical for both efficacy and safety. Always perform a patch test before full application. Avoid contact with eyes and rinse thoroughly after the recommended contact time. These products are typically not left on the skin or scalp longer than specified, as extended exposure increases the risk of irritation.

Thioglycolic acid can be irritating to skin and eyes, particularly at higher concentrations or with prolonged contact. It has an unpleasant odour. Products containing this ingredient should include clear usage instructions and warnings.