Chemical depilatory

A chemical depilatory is a cosmetic preparation used to remove hair from the skin on the body. Common active ingredients are derivatives of thioglycolic acid and thiolactic acids, which are used as their calcium or potassium salts.. These compounds breaks the disulfide bonds in keratin and weakens the hair so that it is easily scraped off where it emerges from the hair follicle.

The main chemical reaction effected by the thioglycolate is:

2 HSCH₂CO₂H (thioglycolic acid) + R-S-S-R (cystine) → HO₂CCH₂-S-S-CH₂CO₂H (dithiodiglycolic acid) + 2 RSH (cysteine)

This break down reaction is affected by the calcium hydroxide or the potassium hydroxide, both highly alkaline. These agents are irritating to the skin, so that cosmetic formulations contain other components to moisturize. As the epidermis is also rich in keratin, the skin may become irritated and sensitive if the preparation is left on for too long. Chemical depilatories are used primarily for the arms and legs. They are not be used on the face unless specifically listed for that purpose on the product's label.

Chemical depilatories are available in gel, cream, lotion, aerosol, roll-on, and powder forms. Common brands include Nair, Magic Shave and Veet and are available over-the-counter.