Hydroquinone

Hydroquinone is considered the primary topical ingredient for inhibiting melanin production. Its components have potent antioxidant abilities.

Hydroquinone is a strong inhibitor of melanin production, meaning that it prevents skin from making the substance responsible for skin color. Hydroquinone does not bleach the skin, and can only disrupt the synthesis and production of melanin hyperpigmentation. It has been banned in some countries (e.g. France) because of fears of a cancer risk.

Some concerns about hydroquinone's safety on skin have been expressed, but the research when it comes to topical application indicates negative reactions are minor or a result of using extremely high concentrations or from other skin-lightening agents such as glucocorticoids or mercury iodine. This is particularly true in Africa where adulterated skin lightening products are commonplace.

Because of hydroquinone's action on the skin, it can be irritant, particularly in higher concentrations of 4% or greater and predictably when combined with tretinoin. Some medications have been created that combine 4% hydroquinone with tretinoin and a form of cortisone. The cortisone is included as an anti-inflammatory. The negative side effect of repeated application of cortisone is countered by the positive effect of the tretinoin so that it does not cause thinning of skin and damage to collagen.

Hydroquinone can be an unstable ingredient in cosmetic formulations. When exposed to air or sunlight it can turn a strange shade of brown. Therefore, when you are considering a hydroquinone product, it must be packaged in a non-transparent container that minimizes light and air exposure. Hydroquinone products packaged in jars are not recommended because they become ineffective shortly after opening