A synthetically produced bleaching agent that mimics hydroquinone found naturally in nature. It inhibits the activity of tyrosinase, the enzyme needed to make melanin. Available from pharmacies in two per cent topical applications and found widely in cosmetics as a whitening and brightening agent, it is used to treat freckles, age spots and melasma. During application a sunscreen should be used and exposure to sunlight avoided. It may cause hyperpigmentation in some skin types, and may induce itching, stinging and redness in skin. Clinical studies have implicated it as a carcinogenic, but evidence is inconclusive. Should not be used by pregnant or nursing women. The EU banned the use of hydroquinone in all cosmetics in 2001. See arbutin, bearberry.

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